Thank you for purchasing X-Plane 10+11 as a Digital Download!
Your X-Plane Product Key—good for both X-Plane 10 and X-Plane 11—is:
X-Plane 10/11 Product Key: XXX-XXXX-XXXX-XXXX-XXXX-XXXX
Save this product key in a safe place, and keep it private, because you'll need it to install X-Plane. (And you'll need it again if you ever want to install X-Plane on a new computer!)
Some distributions came with a key for both 10 and 11, just download the installer for xplane 11 and try if your Product key works! Xplane 11 is not a update, its a new version.