Official comment
Hey Cedric,
As long as you have your first license registered and activated, it's recoverable through your Pioneer DJ account (which you can access through the forums, PioneerDJ.com, or rekordbox.com), under your profile > licenses. Plus, as you can activate the first license on up to 2 computers, there's no need to activate the secondary license unless you need to activate on a 3rd or 4th computer - you could even sell it if you want!
If it's just the DVS you want to register, you could activate that and then sell the dj license.