The trial is Tier 1 only. We cannot offer tier 2 because it would be left unprotected.

This still applies?

The new trial provides Tier 2 access for Windows.

I suppose that part of the protection it is the
"CREATED WITH AppGameKit - WWW.APPGAMEKIT.COM" message, right?
I am asking because while I was searching for this message I realized that the 'Core.cpp' file provides a basic framework in order to be used by a class with 3 basic methods:
Begin()
Loop()
and
End()
Is this structure mandatory for compatibility among the various platforms?

Yes, there is a small watermark.

As long as you stick to the Begin, Loop and End layout you can easily transfer your code across to all the platforms.