You can avoid the "re-sale" of keys with the system that automatically activates the game through the website by assigning the privileges of each account for its activation. (Like this, obviously expired Example Taxi Driver free a few days ago; "SEGA.com is requesting permission to access the following: Redeem and activate CD-Keys on your account). You can put it in the Steam Store for free for a certain amount of time, but it's obvious that you never had any interest in giving it away at Steam, and 4,000 users are practically nothing.