From Idea to Paid Subscriptions in 18 Days: What Took Time Besides Coding

Expiro is a web service that tracks technical inspection, emission inspection, motor insurance and motorway vignette deadlines for businesses. It took 18 days to go from the first test version to live operation with card payments and automatic invoices. The coding wasn't the hardest part. Most of the time went into decisions: what one customer costs, how big the free plan should be, what the data supplier allows, and what we have to promise consumers.

This article is for anyone with an idea for a service with a monthly subscription, whether as a website or an app. We show what we dealt with on Expiro day by day, which decisions were harder than the code, and what that means for your project.

What problem does Expiro solve?

A business with five vans has five technical inspection deadlines, five emission inspections, five insurance policies and five motorway vignettes. Usually they are tracked in an Excel spreadsheet or by one person who "remembers". When that person falls ill or leaves, the deadlines leave with them.

A missed technical and emission inspection costs the business a €165 fine for each inspection, €330 in total, plus a car that isn't allowed on the road. Large fleet management systems solve this, but they add GPS, trip logs, in-car installation and a monthly bill a small business doesn't need.

Expiro does one thing. The business enters its licence plates, for example by pasting a column from a spreadsheet. Expiro looks up the car model and the technical and emission inspection deadlines by itself, shows what needs attention, and sends an email before the deadline. You can try it in the public demo without signing up.

Why is Expiro a good example?

Expiro is a small, clearly defined product: it solves one problem, and customers are happy to pay to have it solved. At the same time, it contains everything almost every subscription service runs into. The data costs money, it sells to both businesses and individuals, customers pay by card and every payment needs an invoice.

That makes it easy to see everything that has to be ready besides the app itself. These are exactly the things we go through on every project before development starts.

What did the 18 days look like?

Notice how many rows in the table aren't about features for the customer. Price list, terms, invoices, consumers, domain, emails. All of it has to be done before your first customer pays you.

Five decisions that were harder than the code

1. Where to get the data and what the terms say

Technical and emission inspection deadlines can be looked up in the register through a paid service. Each car check costs about one cent. That sounds trivial until you read the supplier's terms.

They allowed us to keep the data for only 24 hours. For a deadline that changes once every two years, that would mean paying every day for every car, including cars on the free plan. With costs like that, a free plan would never work.

One email helped. We explained to the supplier what we need the data for and got explicit permission to keep it for a month. Even so, we calculated the price for the worst case, in case that permission ever ends.

Along the way we also ruled out cheaper sources: one banned commercial use, another updated its data only once a quarter. Read your supplier's terms before you start building. They decide the price of the whole service more than anything in the code.

2. A price that survives the worst case

The first draft of the price list looked reasonable until we recalculated it against actual data usage. On the two largest plans we would have lost money on every customer. So we raised prices so that every plan, with its full number of cars, covers its costs including the card payment fee.

The customer still pays less than 50 cents a month per car. The Business plan for up to 30 cars costs €129 a year, less than a single fine for a missed inspection. We describe the whole process, with numbers, in how to price a subscription.

3. A free plan that doesn't ruin the service

A free plan is the best advertising and the biggest risk. The choice was 3 cars, not 1. With one car, Expiro would feel like a service for private individuals, and a business wouldn't try the main thing: an overview of the whole fleet. At the fourth car it hits the limit, and that's when Expiro offers a paid plan.

Free cars are checked once a month, paid ones every day. The order matters more: paying customers have their checks reserved in advance, and free cars only get what is left over. So even a thousand free accounts can't push the service into a loss.

4. Payments and invoices

The customer pays by card monthly or yearly, and a year costs the same as 10 months. The subscription renews by itself, and changing plans or cancelling works without writing emails. After every payment the customer receives an invoice, without anyone issuing it by hand.

That sounds obvious, but it means connecting the payment gateway with the invoicing system so that an invoice is created exactly once, even if something breaks along the way. Prices on the website are final because the operator isn't VAT registered. That, too, is a decision you need to make before you write your first price.

5. A consumer is not a business

The original plan was to sell only to businesses. It turned out, though, that people with one or two cars want Expiro too. That changed a lot.

A consumer may withdraw from the subscription within 14 days and get the full amount back. So before paying, the customer explicitly agrees to the service starting right away. After paying, they receive a contract confirmation by email with the terms and conditions attached, and there is a withdrawal form on the website. Decide first who your customer is: a business or a consumer. Your terms, payments and website copy all depend on it.

Green only when the data is confirmed

We set one rule at the very start and never broke it: a car never turns green until we have confirmed data. When the register doesn't return a date or the check fails, the car stays grey as "unconfirmed", not green as "all good".

This is a business decision, not a technical one. One false green means a fine for the customer and the end of trust in the whole service. We would rather show less, but show it truthfully. Where the register isn't enough, the business enters the date itself from the inspection report.

When the customer doesn't contact support

An annoyed customer usually doesn't write in. They leave. That's why Expiro has a "Something's not right?" button. Clicking it doesn't open an empty box to type in. The customer immediately sees the four most likely causes, for example a wrong technical inspection date for a specific car, each with a one-click fix.

The order of the causes is set by rules together with an AI model that also understands what the customer writes in their own words. The AI never sees licence plates or names and never decides whether a car is past its deadline. It only helps choose what to show the customer first.

How people find Expiro

Businesses don't search for "a fleet deadline management system". People type into Google "fine for missed technical inspection", "when to cancel motor insurance" or "when does my technical inspection expire by licence plate". In Slovakia they type "ŠPZ", the everyday word for a licence plate, not "EČV", the official term. And they search as individuals, even when they decide for a business.

That's why, besides the main page, Expiro has guides on exactly these questions, some with a calculator, for example when to cancel motor insurance. Each guide answers the question first and only then offers to have Expiro track the deadline. We changed the name for the same reason. The original Slovak name, "Strážca flotily", is hard to type with its diacritics, doesn't work as a domain and only speaks to businesses with a fleet.

What's next: a mobile app

The website came first on purpose. Businesses set up their cars at a computer, web payments don't cost an app store commission, and changes can be deployed right away. The next step is a mobile app for iPhone and Android: you add a car by taking a photo of its licence plate, and deadline reminders arrive as notifications straight to your phone.

The app will be a free companion to the web service. Subscriptions are bought only on the website, and the app may not even link to the purchase, otherwise Apple and Google would take a share of every payment. We write more about this in subscriptions in your own app.

What to take away for your project

If you have an idea for a subscription service, answer these questions before you pay for the first hour of coding:

1. How much does one customer cost you per month? Data, text messages, emails, storage, payment fees.
2. What do your suppliers' terms allow? May you store their data and resell it?
3. What does the customer get for free, and what will that cost you with a thousand free accounts?
4. Are you selling to businesses, consumers, or both? Your terms and refunds depend on it.
5. Who issues the invoice, and how does the customer get to cancellation?
6. What words does the customer use to search for their problem? Not the words you use to describe it.

Frequently asked questions

Can a service really be launched in 18 days?

For a small, clearly defined product, yes. Expiro does one thing, and decisions were made quickly. A larger scope or a longer approval process adds time. But it still holds that a smaller scope at the start means an earlier launch and earlier feedback from paying customers.

How much does Expiro earn?

It is too early for those numbers; live operation has been running since 29 September 2026. The pricing, however, is set so that every paid plan covers its own costs from the first customer. We explain how that works in the article on subscription pricing.

Why the website first and the app later?

Businesses set up their cars at a computer, and a website can be launched and changed faster. Web payments also don't cost a commission to the Apple and Google stores. The app will add what only a phone can do: photographing a licence plate and notifications.

Will you build a similar service for us?

Yes. With Expiro we tested the whole process, from the price list to payments and invoices. We will go through the same questions with you before development.

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Have an idea for a service people will pay for monthly? See the Expiro case study, or write us a few sentences about your idea. Together we'll work out whether it pays off before we start coding.