Depending on your version of the game (Retail Disc, Digital, or Steam), the activation process differs: Steam Activation

: SCS Software encourages all legacy users to activate their old retail keys on Steam. This allows you to receive automatic updates and access DLC.

When Euro Truck Simulator 2 first rolled onto the scene in Q4 2012, the gaming industry was in a transitional phase. Steam was growing, but physical retail copies were still dominant. Consequently, the functioned differently than the keys you buy today.

It is important to address the prevalence of "key generators" (keygens) or pirated versions associated with terms like "activation key 2012."