Hi Lewis, I remember reading about this a while back....here is a quick 1min search this morning to give you the idea.
https://www.lexology.com/library/det...c-dece97f55520
My understanding (Surgeon not a lawyer) is that in principle the software company has sold you the software and license, and if for unlimited use ( not time limited in some way) does not have future ownership rights sufficient to prevent you from selling on).
I also think that if you did sell it on, the software company is not going to come after you. I also personally think that provided you deleted the software/license you wouldn’t be doing anything ethically wrong. I think that license agreements like this are silly and non enforceable, and whilst no excuse encourage software piracy.
My thoughts only, ymmv!
Cheers
Hemi