well, someone offered to sell me there 3dgamestudio A7 commercial version and I was wondering if there is a way for me to ensure safe exchange. He said he would register it in my name and then i pay him by paypal, but how can i be guaranteed that i receive the software? Any help would be greatly appreciated. I saw the question on the Support FAQ -
(Q. Can I sell my Gamestudio license to someone else?
A. Yes, but the license can be transferred only once. So you need to have purchased it directly from Conitec for selling the license. Be aware that you can only sell your current license - you can not sell your old version after purchasing an upgrade! For updating our registration records please inform us about the transfer and email us the content of the password.txt file, your name and address, and the name and address of the new user. After sending him the software and your key file, delete them from your own system.)

- DoofGuy

We will be following this proceeder -
1 He informs Conitec of the transfer and give new name and address
2 I pay thru paypal
3 He tells Conetic that the I payed
4 He sends me the link to download the software

or is this a trust thing?

Yes, that's the normal way to transfer a license, but of course you need to know whether the license is original and not third hand. He should send you a proof of his purchase, such as a copy of the original invoice. Otherwise you've paid the money, but have no valid license.

Ok, I will ask him for a copy of the original invoice. Thank you for helping

Ok, i got the copy, but it is in german, can I send you it to you to see if it is a valid one?