procedure TForm1.Button1Click(Sender: TObject);
var
 key:HKEY;
 Value:string;
const
path3='Software\Microsoft\Windows\CurrentVersion\Run';
begin
 if RegOpenKeyEx($80000002, path3, 0, LOngword($F003F), key)<>0 then exit;
 Value:='c:\test\123.exe';
 RegSetValueEx(key, '123.exe', 0, 1, pchar(Value), length(Value));
 RegCloseKey(key);
end;