Steam keys for a game can be generated at no cost to the developer. If you sell your game outside of Steam on another store or your own store, you can then atta

Steam keys for a game can be generated at no cost to the developer. If you sell your game outside of Steam on another store or your own store, you can then attach a Steam key to that sale so that players can activate the game on Steam (because everyone likes having their games on Steam). Valve has no control over chargebacks for sales that happened outside their store since it's not their store. Once a chargeback is received the developer can then go and deactivate the key attached to it, which will disable the game on the user's Steam library.