I know this the question of how to detect if your iOS app has been pirated has come up dozens of times, and the general consensus is that:
- It isn't worth playing that cat and mouse game
- People who pirate your app most likely wouldn't have bought it anyways
- People using your app, paid or not, is almost a form of advertising so can help in a way
But, what about pirates that become (to borrow a term from Google) vampires - people who pirate your app and actually cost you money since your app is very server-side dependent? Is there a recommended way to detect if someone is using your app without having paid for it? Does Apple offer any receipt verification for the paid app itself (not an in-app purchase)?