Something you see quite often are named licenses that then show up somewhere in the UI. "XYZ App licensed to <name>". Doesn't stop people copying, but at least looks bad for them. Doesn't prevent someone cracking your software and just ripping out that function of course. Companies used to put lots of effort into making reverse-engineering that hard and there's probably a few companies still selling tooling around that, but realistically it's probably wasting your time to overcomplicate that. Basic license file just has some serial, the registered name and then a digital signature your software checks, customer can download license file on purchase. I've seen personalized executables/installers too, but that's a pain with e.g. code signing.

Anything else requires phoning home or exotic solutions like hardware tokens.