If you are below 25 VMs you can license your RoBo with NCI Edge Licenses. With the NCI Edge you license VMs instead of physical Cores → Check out the Edge Licenses here since there are some other limitations (e.g. VM Memory maximum): Nutanix Cloud Infrastructure (NCI-Edge)

If you need more VMs, expand more in the future or have other requirements you should use the NCI Licenses
Nutanix Cloud Infrastructure (NCI)