Cross DJ 3.0.0 Update

I'm sort of new to this forum, but tried this about a year ago to no avail. I currently run, and clearly have been running, Cross DJ version 3.0.0 for quite some time now. In the "about" section of the software there is a button that says "update" something or other. When I click the button it brings me to this website and says I have no right to access the update for my software and continuously asks for a serial number. Maybe this is a noob post but I have absolutely no clue what the serial number is for my software. Is there some way I could find what serial number I have or do I have to shell out $50 again just so i can get the updated software. Thanks in advance for any replies, I tried this probably a year ago and received no response.