Hi,
From memory the paid version just overwrites the trial version, unless you choose to install it to a different location.
And on that topic, I would suggest that you not install it under your Program Files folder, as each time you want to use a new library you will need to copy the files to the libraries folder (say something like C:\Program Files\Anywhere Software\Basic4android\Libraries\) which will require you to grant Admin access each time (if you are using windows 7).