Greeting,

I have windows application developed by C# dotnet

I intend to sell my application to users

I want some ideas for how to implement security for my application like "license file" or "serial number"

what do you recommend for me !!!

Any one to help me !!!

http://rhino-tools.svn.sourceforge.net/viewvc/rhino-tools/trunk/licensing/

will get you started. Also you can use commercial toolkits like XHEO but these are expensive and in general wont get you better security.

There is a Visual Basic Shareware Starter Kit available.

http://msdn.microsoft.com/en-us/vbasic/ms789080.aspx

It includes the following functionality:

• Buy Now Web Service (PayPal integration)
• Activate Now Web Service
• Product Registration Web Service
• Product Feedback Web Service
• Exception Handling Web Service (app errors)
• Multi-Threaded Splash Screen

See the docs that come with the starter kit for information on the included functionality.

Apparently there isn't a C# version of this kit available.

Lots of products exist for this. See here for a list: http://sharptoolbox.com/categories/licensing