Here is what I mean by that...say Fortinet, once you purchase an appliance, you have subscription valid for 90 days and if you wish permanent license, you can choose validity (I believe 1, 3 or 5 years) and it covers everything (no need to buy separate license for different blades/features).
With Cisco, its pretty much the same. It might be a bit different with certain products, for example Cisco Firepower or Umbrella, but in a nutshell, its same principle.
I cant say for PAN with certainty, but few years ago, when I was more involved with it, it was like that...once people buy Palo Alto appliance, you purchase the valid support and license would have covered anything you wanted to enable on the firewalls.
Trust me, Im not the only one who thinks CP licensing is complicated/convoluted, for the lack of the better term. AMAZING products, but if I lived 1000 years, licensing would still confuse me, no offence : -)