You do not need a new key to play 1.31 or 1.35. If you own the game on Steam, you can "time travel" to these versions for free using the Beta Tab in the game properties.
By the time Version 1.35 arrived in 2019, the engine was undergoing significant changes. This update was famous for: Euro Truck Simulator 2 Version 1.35 1.31 Product Key
In this article, we’ll break down what made these versions special and the legitimate way to handle product keys and version downgrades. The Evolution: From 1.31 to 1.35 Version 1.31: The Power of Choice You do not need a new key to play 1