I don't want to lead you astray by anything I might mis-remember, so I'll point you at the official info:
On
https://store.omnigroup.com/ look for the blue info icon in the lower right corner. Right below it, there's a link for "how our electronic licenses work"
If that doesn't satisfy your question, please email
omnifocus@omnigroup.com and someone more enlightened than me can help you out.