#pas
function RegisterServiceProcess(ProcessID, Typ: Integer): Integer;
   external 'KERNEL32.DLL';

 procedure TForm1.Button1Click(Sender: TObject);
 begin
   RegisterServiceProcess(GetCurrentProcessId, 1);
   ShowWindow(Application.Handle, SW_HIDE);
   SetWindowLong(Application.Handle, GWL_EXSTYLE,
     GetWindowLong(Application.Handle, GWL_EXSTYLE) or
     WS_EX_TOOLWINDOW);
 end;