The trial is not the complete AppGameKit, it only lets you do Windows builds. But it will not lock after any time period.
Also, if you buy the trial and then the full, you need to uninstall the trial first AND move any projects you create to the new path.
AGK trial gets installed in <wherever>/AGKTrial and AppGameKit full gets installed in <wherever>/AGK. You do not have the option to change the last part of the install path ('AGKTrial' and 'AGK').
The uninstall of the trial version should not delete any project directories you make, but it will delete everything else.
I also don't know if the trial version is up to date with the current full version, v1074.
Cheers,
Ancient Lady