Protection of Shareware program

This is a protection for your program, which doesn't break functionality of your program.

procedure TForm1.FormShow(Sender: TObject);
begin
  if GlobalFindAtom('THIS_IS_SOME_OBSCURE_TEXT')=0 then
    GlobalAddAtom('THIS_IS_SOME_OBSCURE_TEXT')
  else
  begin
    ShowMessage('You may execute this program only once 
                 in this current session. If you want to 
                 run this program again, you should 
                 restart Windows or send letter to us 
                 about it. We'll send key to you.');
    Close;
  end;
end;