. Because TimeShift is not a native "SteamWorks" title, you cannot usually "redeem" an old physical key to add the game to your Steam library. Installation
: The key is strictly required during the initial installation of the retail version. If you have lost your physical key, there is no official way for Steam Support to replace it for a retail purchase. Steam Community Troubleshooting Invalid Key
: Marketplace sites like G2A , Kinguin , and Eneba often list global Steam keys at various price points. How to Redeem Your Serial Code