Flexible Performance Licensing is a method for licensing throughput on IBM Security Network Protection XGS appliances. It is currently available on models XGS 3100, XGS 4100 and XGS 5100. FPL 1 entitles the customer to secure up to 2.0 Gigabits per second. In two years, the network throughput is expected to increase to 3.5 Gigabytes per second in two years. A customer would want to secure a 10 Gigabit Ethernet (10GbE) network, but the customers average load on this network is only 10%.”]
Source: https://securityintelligence.com/what-is-flexible-performance-licensing/