To license your product with a different license key:
- You cannot add an ESX/ESXi 4.x host to the vCenter Server if it is licensed with the free version (vSphere Hypervisor) of the license key. For related information see, Adding an ESXi host to vCenter Server 4.0 fails with the error: Host cannot be added to the VCenter as there are not enough Virtual Center Agent Licenses (1018275).
- If you are managing ESX 3.x hosts on vCenter Server 4.0, ensure to select Reconfigure my ESX 3 hosts using license servers to use this server and enter the IP address of the license server in the text box. For more information, see Configuring a legacy license server to manage ESX/ESXi 3.x hosts in vCenter Server 4.0 (1010704).
In the evaluation mode, you can access and use all features of ESX. The evaluation period is 60 days and begins as soon as you power on the ESX machine. To make full use of the evaluation period, make an early decision on whether to use evaluation mode. If you do not enter a vSphere license key during installation, ESX is installed in the evaluation mode.
Note: Select the evaluation option to enable the evaluation mode. You do not receive a license key for evaluating vSphere.
Based on VMware KB 1010839