This is a legal problem more than a technical problem.
Any protection you implement will allmost certanly be trivial to break or get around.
Just tell people they have to pay to use your library.
snarkofagen
joined 11 months ago
You can stand a crappy UI if your need is big enough.
As to your second question.
I used (and payed for) a library that used your planned solution.
It was a c# library to to manipulate flash/swf files (~20 years ago) it shipped with python and java wrappers, but those only worked on windows. If you go this route try to build for dotnet on linux too.
Good luck