Entering the key directly into the game menu of the standalone installer.
. While version 1.15.1 was a specific legacy update from 2014, a single modern product key generally grants access to the full game and all subsequent updates. Ways to Obtain an ETS2 Product Key Digital Purchase (Steam): When you buy ETS2 on product key for euro truck simulator 2 1.15.1
If your key fails to unlock Euro Truck Simulator 2, verify the following steps: Entering the key directly into the game menu