Cd Key For Flight Simulator X Flight Simulator X Deluxe Edition. Register?

Flight Simulator X Deluxe Edition. register? - cd key for flight simulator x

to sell on eBay when I play with a lot of people ask me if I saved the game, but the CD key. I have only this game once, and that everything that I've played ever and the only on-line time, I too had entered the CD key if they are installed, but no "It would be no problem if someone this game has purchased and register?