Turns out the patent has nothing to do with "things X-Plane has done for decades".
Kind of and kind of not. The patent the troll is claiming has been infringed on is for things others have done for decades - remote license checking:
Section 107 of the patent, which they claim I violated, contains: “107. code for verifying the license data stored on the licensing medium by communicating with a registration authority having verification data.”
The article goes on to point out a few others that have been doing this for decades. HP Openview has been doing it for as long as it has existed. I'm sure scores of others not listed have as well. Honestly, it's been a common practice for decades to be certain.
This is just another example of how software patenting is bad for the industry. Trolls can get patents on nearly anything, then file a lawsuit that while doomed by prior art will cost the victim a lot to show that prior art. Which the Patent office should have found before granting the patent in the first place.
What is worth doing is worth the trouble of asking somebody to do.