We have processes and timelines for installing new software on our production server... which has led to the following question...

If I have my sys op guys install the demo version on our live production server, and they are confident that it works fine and doesn't break anything on the server, and we then buy the licenced version... does the licenced version require a new install of Prince with a licenced copy of files, or is there some key file or other that just has to get placed on the server, added to the demo version to turn it into a licenced version?

Errr, let me put this more simply...
What is the process for going from the demo to the licenced version of Prince?

When you purchase a Prince license we send you a license file that you place in a directory of the Prince installation (or install it using the License window in the Windows GUI).

It does not involve installing a new copy of Prince, just unlocking the existing installation.