Not sure why I thought this was going to be free, but for whatever reason I was surprised to see the prompt for payment after finishing the trial.
It's something the owner should test, and see if it puts people off or if it converts better. Maybe it puts off 10% more people, but 30% more convert? Good on them for finding that out and optimizing accordingly.
We in the dev world expect way too much for free. Not that I complain when I find something for free, but people deserve to be compensated for their work also.