License Generator it’s a .Net library that lets you to add a License System on your .Net Application.
See the video to know how work: http://blip.tv/file/3994184
Download a demo: http://www.mediafire.com/?hdmmqd36q5z7g3a
It generates one License for one PC, this want to said that if the user want to use your program on other pc his serial, key will don’t work 
Very simple to use. Simple add a reference for the dll and works with it.
In addition you can make a Demo limitation to your program, with the key:
11111-11111-11111-11111-11111
Works in:
- Net Framework 3.0 or +
- vb.net and C#
The Item includes:
- Dll Library (Obsfucated and Normal)
- Source
- Help Video
- A demo project
Important:Your client needs to have Internet conexion when load your App if you want the mail with the key.
Important:Open the Source and the Demo Project at least with Visual Studio 2008