Piracy is a problem for developers on any platform, and pirating an app on Android is not that much harder than doing it on Windows. Some would say the piracy on Android is a lot higher than on iOS, but some developers have disproved this. Since most of the piracy happens in China, for both Android and iOS, where people wouldn't pay for the apps anyway, the piracy rates between the 2 platforms are not that different.
However, since Android started being known in the media for being a piracy haven because it's more “open”, Google has started working on changing this perception. The prevention is spelled out as an app encryption “feature” (also called DRM) that was announced for Jelly Bean at Google I/O this year.
The problem is when a user bought an encrypted app, the credentials were stored in /mnt/asec, which got wiped out after a device reboot, making it impossible for the user to use the app without those credentials. Since the app was encrypted, and there was no way to verify if it's the same person that bought it for that specific device, you can see the problem on hand for many users until recently.
This has broken thousands of apps in the Play Store, and made many developers angry with Google. Therefore Google was forced to disable this year, most likely until a future version of Android. The current version doesn't seem equipped to handle the app encryption properly, and it might not be able to fix it with a simple patch. Updates are incoming and news continues to filter in slowly, so when we know, we will as always, let you know straightaway!