This may or may not work on Windows so unless someone posts a comment explaining how, you should only download this if you have a Mac.
This torrent contains three cracks for different games by Spiderweb Software;
One for Avernum 4
One for Avernum 5
One for Geneforge 4
Applying the cracks couldn\\\\\\\\\\\\\\\'t possibly be easier, simply Navigate to your hard drive, then to users, then select your user, the go into library, then Preferences.
If you have already installed the demo version of the game then you should see a file like \\\\\\\\\\\\\\\"Avernum 4 Prefs\\\\\\\\\\\\\\\" now all you need to do is put the file from the torrent into that folder. It should say that a file with the same name already exists.
Tell it to replace the file.
Now open the game and you should have the registered copy of the game.
This will work every time you try it.