That's true, but considering how widespread the software is, it's likely that they only need a tiny percentage of the overall user-base to pay to remain a susta

That's true, but considering how widespread the software is, it's likely that they only need a tiny percentage of the overall user-base to pay to remain a sustainable business. They could at any point have changed the software to prevent it from functioning after the trial has expired - they're not going to be so naive to think people will all pay just because of a prompt that can be easily dismissed.