change beetwen Free license to Pro Trial

I'd installed the Unity 3.3 Free version and had activated it. Now I want to install the Trial version to test the Android Platform Builder, but even after reinstall software still activated as Free version. What can I do? Can I build games to Android Platform on the Trial version?

I am not sure what you can do if you tried re-installing it. (I did the same thing, I downloaded the free Unity, but opted not to use the trial pro) As for your other question, if you can build games to Android platform, I believe you can but it will have trial watermark across the app. please refer to this question/answer for more details about pro trail usage.