What happened to my original account?

I just had to re-join this forum that I had registered for a few years ago. I haven't been using my Davinci Studio for a couple years. I can use the Davinci Resolve on my old iMac but cannot open it on my MacBook Pro, which I have been using it on ever since I bought Davinci Studio with the Speed Editor. Now I'm being asked for my license activation number in order to open the app! I have no idea where this is as I've been using the program for years.
Please help!
Please help!