You can license an ESXi host that is connected to vCenter Server or if your vSphere Client is connected directly to the host. You can also query which features are licensed on a host or set a host to evaluation mode.

When you add a host to the vCenter Server inventory, you can assign a license key to the host.

If you are directly connected to the host through the vSphere Client, you can assign the host a license key.

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..