G2A is a digital marketplace where business-verified sellers from all over the world offer a wide variety of digital items. The question of where the keys on G2A come from is a simple one to answer.
The keys sold on G2A come from video game developers and publishers. Wholesalers and retailers then buy them and put them up for sale on the marketplace following a thorough business verification process.
G2A has also implemented various other measures to assure the legitimacy of keys and protect both buyers and sellers.