There are 3 ways you can verify how many ports are "licensed" on a particular appliance:
Through the "Select Ports" window:
NOTE: Be aware the port reservation is not index based, you can reserve any port you want up to the maximum of licensed ports. i.e. On the images above, the Licensed ports = 4, hence, you can reserve either the first 4 ports, or the latest 4 ports, or 4 ports on the middle, or any 4 ports combination you want, up to 4 ports in total.