Actually - on Android, if you want to 'verify' that your app was not pirated (i.e. the paid-for APK was not just copied from one device to another), you have to call their licensing service: http://developer.android.com/google/play/licensing/index.htm.... Of course, many paid apps choose not to add this additional layer of verification, but it is functionally similar to the Firefox OS solution (except with a web app, you don't even need to copy an APK - you just visit it on the web).