Subscription or pay per use: the numbers for three real projects

What you'll see in this lesson

1. Two ways to pay for AI coding

   With a subscription you pay a fixed fee with usage limits; with the API you pay for every token the model reads and writes.

2. The models we use for the math

   We compare an expensive model, a mid-range one and a cheap one with their official API prices for October 2026.

3. How to estimate a project's tokens

   An agent doesn't spend per message you send, but per step: in each one it resends the whole context and writes a little.

4. Project 1: a simple website

   A five-page website with a contact form: about 150 agent steps spread over a couple of afternoons.

5. Project 2: a small game

   A 2D browser game with five levels and high scores: about 600 steps, because gameplay gets tuned by testing.

6. Project 3: a business management app

   Clients, invoices, users with permissions, a database and tests: about 3000 steps over two months.

7. The costs you don't see at first glance

   The numbers above are clean; in reality, these six things inflate the bill.

8. When each option pays off

   Rule of thumb: occasional use, API; daily use, subscription; inside your own product, always API.

9. Summary: do the math before you pay

   Estimate steps, context and price, add a margin and choose the option that fits your pace of use.