For some of this stuff (Autocad, I'm looking at you...) it used to be the case that you could shell out a one-time $$$$ and get a license for v5.0 that would work for all eternity. The companies even gave you minor upgrades to support new OSes.

But since these guys have now switched to a subscription licensing model, they no longer do that, so there are scattered XP boxen around running ancient versions of various expensive software that just keeps working.