Microsoft licencing currently isn't like that. If you have a VM, you can license the VM itself or the host if you want to run multiple. You need to calculate the break even point for that. But if you are doing it per host and using VMs you then need to licence all the hosts. Per VM is the VM, move it if you like, but to move it more than every 90 days you need to have software assurance. You can licence just a single host, but you would need to move all the VMs at the same time to the new host, again, needing SA or limiting it to every 90 days.
You also have the server licence instead of core licence model, but you require CALs and that is limited to standard only, so you are limited to 64GB RAM i think it is now. It also means it is really only useful for internal services where you can assign users or devices. Internet facing things using the DB need to be per core.
Biting the hand that feeds IT
