Designed to cost you money
This app is designed in such a way that when you forget to "end" your session they will continue to charge you. Its a very poor user experience, and the FAQ basically says "too bad."
So when I parked for 20 minutes this morning and forgot to hit the button when I left, it never said anything until 12 hours later and it cost me $20.
App deleted, will never use again. PayByPhone (used in Seattle) has a much better design that does not allow this to happen.
Chris_342 about
ParkMobile - Find Parking, v4.2.2