For people having problems getting the trainer to activate (applies to GOG version, not sure about any others):
1) Download/extract the latest version of the trainer
2) Start the game
3) Load your save/start new game (not an online game)
4) (The most important step) Alt + Tab out to the desktop and run the trainer as Administrator
5) Hit F1, it should say Trainer Activated
6) Use any of the other options, then Alt+Tab back into the game, and you should be good to go
7) Whenever you want to use Add Gold/Exp, it is best to Alt+Tab out first, then use the option, then Alt+Tab back
Known issues - using (not just activating one time, but actively using) the trainer options multiple times while in the game can (and eventually will) cause the game to CTD, as will Alt+Tabbing back and forth between the game and the desktop too often. For the add gold option, this is especially true - adding gold up to 4 times in one game session should be ok, I've found that trying for a 5th time always causes a CTD no matter if you do it in game or by Alt+Tab to the desktop first.