Our licensing suite Software Protector (based on SKGL) is mentioned as an example of a licensing framework in Licensing .NET Applications by Fabian Deitelhoff at Pluralsight http://www.pluralsight.com/co…/licensing-dotnet-applications.
See the story behind SKGL in the InfoQ Interview:http://www.infoq.com/news/2014/12/SKGL
SKGL – Serial Key Generating Library is an offline based key validation system where license information is stored directly inside the key. It’s used by individual developers as well as companies. Designed by Artem in 2010-2011.
Interested in different kinds of key generation algorithms? Check out http://www.codeproject.com/Articles/764610/Licensing-systems-in-NET.