Open Steam > Games > Activate a Product on Steam. Enter your key.
: Ensure you aren't trying to activate a Steam-format key in the legacy launcher or vice-versa. Steam keys usually follow an XXXXX-XXXXX-XXXXX Version Mismatch
Open > Games > Activate a Product on Steam... > Enter your code. Legacy (Non-Steam)
If you are looking for a product key for Euro Truck Simulator 2 (ETS2)
: These keys follow a five-by-five format: XXXXX-XXXXX-XXXXX-XXXXX-XXXXX . This format is typically found in older physical retail boxes or purchased directly from the official SCS website Steam Edition
Pirated or "cracked" versions are stuck on one version, meaning you miss out on years of new trucks and features. Modern Licensing via Steam