any other to be added quote a example for windows 2000 machine..
I'm not sure what that means.
and how to access feature value in windows 2000 machine.?
You can't. Like I said Windows 2000 lacks the necessary features to fully support TurboActivate. It's an ancient system -- more than 12 years old. Microsoft stopped supporting it 4 years ago. I would recommend that all users using Windows 2000 upgrade to at least Windows XP.
is we need to activate after "IsProductKeyValid() " function returns true.
You can't activate on Windows 2000. If you absolutely need to support Windows 2000 you can use "IsProductKeyValid()" valid function as a binary way to limit your product (either they're licensed or not).
For instance, you can add code to your app that uses ""CheckAndSavePKey() " and "IsProductKeyValid() " for Windows 2000 systems, and uses proper activation for Windows XP and above.
Though, before going down this road I would first confirm that any of your customers actually use Windows 2000. My guess is they don't. This sounds like a requirement that doesn't exist in reality.