title: License key library for C# windows application that is open source / free
body: <p>Any recommendations for an open source (free) C# library/application for a C# Windows Application that could be used for: (a) creating license/product keys and (b) has library that can be used within the code to perform a check to see whether the entered license key is valid?</p>
  
  <p>(I've seen other posts which cover commercial products, but here I'm looking for a ready-to-go tool with library that can be used in a C# windows application)</p>