You can license an ESXi host that is connected to a vCenter Server system or to a Linked Mode group. You can also query which features are licensed on a host or set a host to evaluation mode.

You can assign a license key to an ESXi from the Licensing page in the vSphere Client.

You can view which features a host is licensed to use.

If you have assigned a license key to an ESXi host, you can switch to evaluation mode to explore the full set of features that are available for the host..