title: Android - in-app billing and existing customers
body: <p>I'm planning on discontinuing Pro version of my app (DroidIn) and offer in-app billing instead. How do I support existing Pro customers in such case? Is there a way to grant user paid license without charging them a second time? Currently I require user to have both regular and Pro version running on the same device where Pro is simply a validator (~75K)
  Any creative suggestions are highly appreciated </p>