How can I provide compulsory license key option in any software developing in Dotnet and C?

I m developing a software in Dotnet, I want to provide license key or code to be added to the software so that full working in the software needs the license key or code from the Licenser

How can I provide compulsory license key option in any software developing in Dotnet and C?
there are many class in .net for eg. Random that produce random numbers. u can generate them at runtime.


then u can save them a configuration file like App.config for windows .net based applications or Web.config for web based applications.


then a particular user can be authenticated for the licence key from this configuration file.


This is just one of the methods since this can be done in a variety of ways. one other way would be to store these numbers in the back end allowing access only to the installer.
Reply:Check this out http://www.codeproject.com/KB/install/Li...
Reply:For licencing ,u can write ur logic ,or u can use public key private key concepts.You can generate an guid then distribute it,and make bound to the end user to enter the key for the first time,then you can check the key if matches then enter.U can code a small utility whiche will generate a file withe some hash code according user name logic then can match the file.