如何在C＃WPF应用程序中验证每个菜单项的许可证

I have created an application in WPF C# and obfuscated through Dotfuscator. Now I wish to give License key for my vendors. There are Four Menu's in my application and each Menu have separate cost. So I need to give separate license key for each Menu's to verify it. I have created an application in WPF C# and obf