You have two official options depending on your needs:

Product keys (or CD keys) are only required when you first purchase the base game or a specific paid DLC (like Iberia, Scandinavia, or a truck pack). Once your game is activated on Steam, you never need to enter a key again—even after hundreds of updates.

If a website claims to sell a “Product Key for ETS2 1.40.4.8,” it is one of two things:

Here’s the good news: Euro Truck Simulator 2 is frequently on sale, and you can legally access any past version with a few simple steps.