Greetings @Manex! One license works for 2 machines, so for example if you want to use Excalibur on 3 machines, I would purchase 2 licenses (this will give you 4 machines in total).
There are two ways to purchase licenses:
1) You can purchase each license separately, each license will work on 2 machines.
2) Or change quantity during checkout, you will get 1 license code, but it will work on 2*Quantity machines.