I'm concerned about wallet validated purchases....  Burn to play.   DRM systems have traditionally been closed source, but in-wallet closed source is going to turn away much of the tech croud.  Without them your project will not only suffer from lack of good developersbut also a community who finds that the coin is broken/bad everytime they seek support.

Also note that application liscensing has long been a target for hacking, so the likely-hood of building a copy protection off interacting with another app will simply result in a clone of the other app.  As for in-wallet applications that are closed source.... are you stupid!  Torjan a maleware will quickly make this a no-go.