Upgraded laptop, enter the license key but keep getting error 5

My old laptop is getting slow and beat up.
I just bought a new laptop.

I installed Rekordbox (one of the first software programs that I installed - rekordbox 5.8.6 ). The software is working well on the new laptop on "demo" mode, it says 30 days for free to try the software. However, I already have a license key, so I enter the key and appropriate email address and password but it keeps saying Error: 5 - Please help!

Thank You, Marinko (DJ and Music curator based in Niagara On The Lake, Canada)