Missing mail software key Audirvana


Trying to use the new version 3.5. of Audirvana on the Mac, I got stuck.

I am on vs 3.2.16, but the mail with my key is lossed, I can only find an earlier key from a lower version in my notes.
Maybe it was a mail on an abandonned Email platform, I think so. Or on gmail, in which case I seem to have lost the specific mail anyway.
Any way to regain my key, having an payed version 3?