A second license for (old) Parallels Desktop for Mac

Greetings,
I have Parallels for Mac Desktop 10 for Mac (10.2.1 (29006)). Yes I know it is old, but it does all I want for the time being.

I have cloned my "old" Mac to another Mac, using Carbon Copy Cloner. I want to use Parallels on both computers.

So I need to purchase another license for Parallels (10) for use on the "new" computer, but it is not clear how I do that.

Is it possible to purchase a second license/activation code I can use? Only one computer will be used at a time, but I'd like to not have to re-activate Parallels each time, and happy to pay for a license.

Thank you.