Modern versions of ETS2, including version 1.40.4.8 and newer, tie your game ownership directly to your Steam digital library.
Once you have your product key, you must redeem it on Steam to add the game to your library. Ets2 1.40.4.8 Product Key
Regardless of the format, the key is a . Once it is used to activate the game, it is permanently bound to your Steam account (or your legacy offline account, depending on your version). Modern versions of ETS2, including version 1