If you are not local to the host and cannot access the direct console, use the vSphere Client to access the ESXi license key.
- From the vSphere Client, select the host in the inventory.
- Click the Configuration tab.
- In the Software section, click Licensed Features.
The license key and a list of features that you can configure on the host appears. The license key appears in the form XXXXX-XXXXX-XXXXX-XXXXX-XXXXX.