Purchase an official Xentry PassThru subscription from Mercedes-Benz. It is more affordable than the full dealer kit (approx. $500–$1,000/year) and does not rely on a traditional Startkey.
Mercedes-Benz employs the Startkey system for three primary reasons: startkey xentry
Every StartKey is generated based on a unique Hardware ID (HW-ID) found on your PC. startkey xentry