Errr...you said someone uses a Professional version of 3D GameStudio. Has someone bought a copy of 3D GameStudio Professional from Conitec?

Also, 3D GameStudio is licensed on per-developer. In other words, a developer can install 3D GameStudio in more than one computers, as long as only a developer can use 3D GameStudio. Thus, you can't let someone else use 3D GameStudio.