If you have physical access to the host or remote access to the direct console, you can use the direct console to access the ESXi license key.

From the direct console, select View Support Information.

The license key appears in the form XXXXX-XXXXX-XXXXX-XXXXX-XXXXX, labeled License Serial Number.

Note

The physical machine serial number also appears, labeled Serial Number. Do not confuse the license key with the physical machine serial number.