from support page
Q. Can I sell my Gamestudio license to someone else?
A. Yes, but the license can be transferred only once. So you have to have purchased it directly from Conitec for selling the license. And of course, you can only sell your current license - you can not sell, for instance, your old version after purchasing an upgrade. For updating our internal registration lists please send us the content of the password.txt file, your name and address, and the name and address of the new user.