It used to be that to update the trial to the licensed version with the box, you just inserted the DVD & ran the installer to convert the trial to licensed. This has changed with Snow Leopard. You now need to delete the trial & then reinstall from the boxed DVD. The files to delete are the iWork ’09 folder from the main HD > Applications; the iWork ’09 folder in HD > Library > Application Support & the individual iWork application plist files found in HD > Users > (your account) > Library > Preferences for each user.
Yvan Koenig has written an AppleScript that removes the files. You can find it on his iDisk in For_iWork > iWork '09 > uninstall iWork '09.zip.
