How do I register my site with a new license key and not lose everything

I have a Flatsome theme all humming away ok, then theme update done to the latest version and my site gives me this message
The purchase code is already registered on another site. Please go to your account and manage your licenses.
Now the site was written by someone else who has since disappeared so Im fine with buying the license but Ive search everywhere on how to change over the license, do I just un register and re-register with the new license key?
I dont want to lose my WP site just get rid of the Flatsome crap plastered all over it

You should to try to manage the licenses there.

If no luck contact the author of your purchased theme, the theme author will assist you.

How to contact an author to get support or for any technical query:


The author disappeared but I bought a license anyway and applied the code and activated my child theme all done back on the air