Everyone be warned.. don't deal with this Guy until he Don't clarify my Issue. few days ago I've bought a GTA V steam game from him. he sent me the game through Steam Gift. but today I got a Message from Steam that they removed the game from my account library because the payment of the game wasn't done..
he's probably a scammer and selling stolen/cracked accounts that can be everytime removed from your accounts.
see this:
http://imgur.com/a/Sm3nR
I got this issue before , and there is two explanation (since you didn't do the payment your self) :
1. He is a carder (using stolen credit cards)
2. He chargebacked somehow the payment from steam. (basically bought the game and then chargebacked the money)
There is probably nothing else to clarify, feel free to open a scam accusation If you didn't already.