PAYG licensing is linked to the machine type used to run FortiGate VMs. License fee is calculated per hour of instance running and added to the Google Cloud invoice. To stop charges it is enough to stop the instances. It is the most flexible type of licensing available for FortiGates in public cloud.
PAYG licensing requires using special PAYG boot images published by Fortinet. All images with names containing "ondemand" or family name including "payg" published in fortigcp-project-001 project are PAYG images. To deploy a cluster with PAYG licensing set a proper value for image_name or family_name variables. By default the module deploys newest firmware in PAYG licensing.
See docs/images.md for more information on obtaining images.
See main.tf file for example code.