Was a copy of PowerDVD included in the auction? If not, you just bought a burner, not the PowerDVD software. Just uninstall it if you don't like it, or buy another key from Cyberlink if you do.
The fact that PowerDVD is asking for a license key has nothing to do with the player.
If you're just a casual DVD viewer, just get VLC player available at
VideoLAN - Free Software and Open Source video streaming solution for every OS! . Open source, free, and just plain works.
good luck.