so if the customer buys a new machine and throw out the old one, the customer doesn't have to buy an additional seat.
I agree but only if the machine being thrown out DID NOT previously have an ERAS license assigned to it.
If the machine was assigned an ERAS license, then if the machine is thrown out, the ERAS license goes with it. Ie. if the customer bought 100 licenses and all were assigned, they would now have only 99 licenses, all assigned.