You're still misunderstanding. Here's how it originally worked:

(1) For the first 15 days, you could make recordings of any length.

(2) After 15 days, you could use the app for only 15 minutes.

(3) If you paid, then you could once again make recordings of any length.

The bug was that "15 days" in (2) accidentally became 15 minutes, so that after only 15 minutes of trying the app, you were limited to using the app for only 15 minutes, which of course would happen the first time you used the app.

Perhaps you're confused because there were two factors both with a value of 15.