old ID for Kontakt is gone - how to use it today?

Hello to Berlin,

I bought a Kontakt 3 version years ago and registered it in my name.
Since that was at least 2 decades ago, I also used a different e-mail address at the time - I just can't remember which one.

How can I now link my software to my new address and e-mail address?
And more importantly: How should I buy the new kontakt 8 version?

I am the original purchaser of the software.

Best regards
Alan