Game code can be scammed?

A gamecode I believe could not be chargeback, because you're the owner of the game code now. Unless they bought the code on steam.... I'm not sure.

Anything can be revoked, no matter if its gift or key, just trade with trustable members, and know for what you trade. Key that are likely to get revoked if you trade with scammers, are from Humble Bundle, and other site like these.