FortiGate-VM supports several licensing schemes, each designed for different use cases and purchasing preferences. According to the Fortinet Ordering Guide, "FortiGate-VM is available in the following license schemes: term-based subscription, FortiFlex points-based consumption model, and public cloud PAYG".
For local or private data centers, downloading the specific deployment package allows installation on: Nutanix AHV OpenStack KVM / QEMU 4. Understanding FortiGate VM Licensing Download The Fortigate Vm
To run a basic FortiGate VM instance for testing or evaluation, your host system should meet these minimum specifications: 1vCPU to 2vCPU FortiGate-VM supports several licensing schemes