How to programmatically determine if DRM was removed from iPhone application?

Question

How can I determine if DRM was removed from iPhone application bundle (to protect it from piracy)?

Answer 1

I have an iPhone app which integrates with a third party web service. I use the technique described in this question to find pirates and then have the app "phone home" with the user's device ID and user ID for the web service (I haven't done anything with this information yet, but I was thinking about contacting them and asking them nicely to purchase my app).

In addition, once a user has used my app for a certain amount of usage, I limit functionality and direct the pirates to the App Store for full functionality.