If you bought a physical controller that says it comes with a "keycode," this is typically for a Limited Edition (LE) version. You register that code once on the VirtualDJ website to link it to your account.
Below is an overview of how the current licensing system works and why you don't need a traditional serial number anymore. 1. The Death of Serial Numbers Virtual dj v5.7 new serial number
The era of typing in long strings of characters is over for VirtualDJ. If you bought a physical controller that says