As mentioned above, did you click the Register button and if so what happened? If it said your key was valid, then check your installation location - make sure you haven't installed FSUIPC6 under your Documents folder, especially if you are using OneDrive or some other cloud-based storage mechanism for your Documents. If all else fails, you can manually create your key file. Create a file in your FSUIPC installation folder called FSUIPC6.key, with the following contents, substituting the