New Host - Need license for backup computer



I have an existing job that wants a backup computer ready to go in case the existing system fails. This existing system is AX and would only be used as a backup if needed. We have never used tenant billing and we took over this job from another company. We are unfamiliar with licenses pertaining to this driver. What would be required to get a license for the backup computer? Can you help me with a contact to get this setup please?

Thank you,