Run application only in Admin account

You need to use Security.Principal namespace to access WindowsIdentity namespace as

using System.Security.Principal;

and then you can use given function to check application is running in admin account or not.

public static bool isAdm()
        {
            WindowsIdentity identity = WindowsIdentity.GetCurrent();
            WindowsPrincipal principal = new WindowsPrincipal(identity);
            if (!principal.IsInRole(WindowsBuiltInRole.Administrator))
            {
                return false;
            }
            else
            {
                return true;
            }
        }

In Entry point of your application try to write given code

if (isAdm())
            {
// Execute block when isAdmin return true 
                Application.Run(new Form1());
            }
            else
            {
// Execute block when isAdmin return false
                MessageBox.Show("You must run this application as Administrator");
                Application.Exit();
            }