When you purchase an on-premise license of FusionReactor, you purchase a number of server seats.

We class one server seat as one single physical or virtual server running FusionReactor. So, if you have (say) 6 virtual machines, then you need 6 seats on your license key.

FusionReactor SaaS (CLOUD) enables you to either make RESERVATIONS for how many servers you would like to purchase each month – or you can use the ON-DEMAND licensing so that we charge you based on your actual usage

Each physical or virtual server (host) requires one FusionReactor license. If you are using SaaS then up to 4 instances or 4 Docker Containers are covered with a single license seat. If you exceed 4 instances/Dockers, then you will require a second license e.g. 4 instances = 1 seat, 6 Docker containers = 2 seats, 13 instances = 4 seats, etc..