I am not with Laminar Research; just another flight simmer.
At some point after the initial installation and then starting X-plane you have missed a "prompt" asking for your digital password key or telling you to insert your disc 1.
The disc version requires disc 1 to be inserted into your disc drive at all times. Unfortunately there is no password or key available as a substitute for the discs. If you don't when you start X-plane it will go through the same prompts mentioned above and automatically revert to the demo version as you are experiencing.
To run x-plane turn your computer on, insert disc 1 and then start X-Plane. The disc should be automatically found during the boot-up.