If you have issues whereby your virtual server regularly loses its Impero license settings, this may be down to fingerprint changes on the hardware of that server operating system.
The Impero Server takes a hardware fingerprint upon installation – if any changes to this fingerprint are detected, the server de-registers, thinking that this is an unauthorized installation. This could happen, for example, if that MAC Address changes – you are required to ensure your MAC Address is static.
On the Virtual Console, open the “Network Adapter Settings” and check the MAC Address. If it is set to “Dynamic”, change this to “Static.” Usually, the server requires to be powered off before you can make these changes.