Windows Forms doesn't have a built-in membership system like this, but you do have rich support for Active Directory in case your company is using that. See the System.DirectoryServices namespace (consult Google).
Windows apps normally run in a more permissive environment unless it's locked down with Code Access Security. In that case it's possible to control which company users are allowed to use which apps, and you can even lock it down to individual functions in a program, perhaps tying them to roles in Active Directory. Your app can then test to see if the current user is allowed to use those functions, or if you choose not to test, you can just let the app abort with an exception.
Smart Clients are Windows Forms apps deployed over the web. These run in a tighter security envelope, but they still have some useful permissions, like being able to call a web service at the URL they were launched from, and the ability to write to the isolated storage area of the hard disk. You can further open up permissions using CAS and intranet security policies to control user permissions.
It's always been easier to do this stuff in Windows, but you have to code the implementation yourself.