During 2021 so far I’ve released a .NET Core license key generator and verifier library, of which the source code is freely available via GitHub. The following binaries can be incorporated freely via NuGet packages into your own projects:
The BarbezDotEu.License.Generation NuGet package is there to generate license keys, and a BarbezDotEu.License.Verification package verifies any license key it is given. Alongside the packages comes a License Key Generator demo application, made available via github.com as well.
Until we meet again, take care!
Hannes