Without a valid, registered key, you cannot receive technical support or official patches. The Best Way to Get a Working Key Today
It supports thousands of assets from older versions.
Purchasing on Steam automatically handles the CD key and activation.
For a DRM-free version that doesn't require constant "phoning home" to a server. Troubleshooting Activation If you have a key but it isn't working for Build 46957:
Look for a sticker on the back of the manual or inside the DVD case flap.
Locate where the game is currently on sale
A key for "Trainz Simulator 12" will generally work across all builds, but regional versions (like the Russian or German editions) sometimes have locked keys.