Security of Paid apps in Google Play? What measures does Google takes to ensure that paid apps that are downloaded do not get spread for free? Currently I see a possibility that can leak out a large number of apps:


Someone pays to download an app on his mobile.
Creates a backup of the app.
Gives the backup to friends/ family or spreads it over the internet.
Many people use the paid app for free.


I have not tried this. My Question is: Is it possible? What is the current state of the security measures for the paid apps on Google Play?
In addition to Martyn's answer on encryption.

This might be a bit on the developer side, however, Google offers Application Licensing:


  With Google Play Licensing, your application can query Google Play at
  run time to obtain the licensing status for the current user, then
  allow or disallow further use as appropriate.