I bought v3 and had nothing but weird intermittent trouble with the MIDI port driver it installed...with no way to uninstall, even if you uninstall AutoTheory itself.
The Win10 upgrade from Win7 finally killed it. The dev never showed the slightest interest in the problems his implementation caused. He'll never get another dime of my money.
Besides, there are other, very similar tools that behave nicely, and have responsive devs.
In case I haven't been clear, my opinion of Auto Theory is:
