So, I am near end-game and have achieved the pirate rank of Khan, which I was excited to do as Dominion relayed via its Rachekhan's Scale I could order an attack on a dominator system at this rank (which would help me clear out the remaining 8 systems of Keller doms); however, this isn't even an option at Dominion...Can't use the portal generator (tells me to "piss off" and purchase a license [which I did and still nothing]); can't relocate base; can't order attack on coalition system; and can't mess with military, each option relaying it's "too expensive" (and I'm around with over 20 million in currency...)
You need to purchase a license, and then after you've purchased it, do a LOT of piratey things - well OK primarily stealing credits from people (talk to them and demand their money), since the pirates gain a percentage of all credits you grab.
They don't get anything out of it if you steal cargo, but that may possibly still help get your hidden "piracy rating" up (which is independent of the thing that tells you the type of ranger you are, although that will most likely go into the "pirate" range while you do this).
It's a somewhat annoying mechanic, but the more stuff you steal from people while having a license, the more "cash" you'll have banked up (again, hidden from you). So they take that into account when determining whether a mission is even possible - after your pirate rank of course. And then you still need to pay for it, and even then it might not be possible due to circumstances...
Also, with the "relocating" the base, each base has an internal pile of "fuel" that seems to regenerate over time, but it's limited. Which means if the base has recently moved (within the system, or transported to another system), then you may need to wait a while for them to "recharge".
It's been a while since I went nuts with pirates so not sure if this also affects their ability to mess with the military or draw ships into the system...