Demo and paid application - how to implement?

I have nearly completed my application and about to upload it into Android Appstore. I need to divide demo and paid versions - one is free with limited capabilities, another one - paid with full functionality. The question is: how to implement it - the only idea which I have in my mind is following:

Upload 2 independent applications placed on different packages. But in this case there's one obstacle: let say user installed demo application packaged as my.foo.demo then user decided to buy full version which will be installed in package my.foo.paid. In this case I need to provide user with ability to transfer user files/data/preferences from package my.foo.demo to my.foo.paid. Wow, but it's not very simple task (keeping in mind Android's security model)

Proba开发者_StackOverflow中文版bly there's another approach? Any ideas?

The easiest way would be to upload two independent APKs. There is a way to have a user download a free version, and then download a "key" application that unlocks the paid functionality. That can lead to lots of user confusion since sometimes they will download the "key" application and not the base application. So if you can upload two different versions, that will eliminate that hassle (but means you have to maintain two versions).

So now to answer your question about sharing the data. The simplest way would be to have a content provider for your data and just export that to the paid version. Alternatively, you can look into the sharedUserId attribute in the application's manifest. This will allow you to run in the same process and access the same files.