If you see “Invalid license key” , the key is either for the wrong product (e.g., vCenter key on ESXi) or is already used on another host (if not a free edition).
Navigating the complexities of VMware ESXi licensing has become increasingly critical following Broadcom's shift away from perpetual licenses toward a subscription-only model. When faced with a "license key expired" error, your virtual machines (VMs) will fail to power on, effectively rendering your server unusable. vmware esxi license key fixed