I've searched for trial application expiry methods and I've found good answers regarding Trial periods for apps but they're time-based.
How can I create a Trial app version that expires after clicking a button 3 times?
based on this link Creating an Android trial application that expires after a fixed time period (option 2 on the accepted answer) I would like to hard code the number of times they have used it, so even an uninstall/intall would have no effect, is this possible?