I kept upgrading until 3.0 was the end of the road for the desktop program.
I used to use CoolEdit and moved to Audition when Adobe acquired it. The functions for cleaning background noise and clicks/pops have (last I checked) no equivalent, even within Adobe's own replacement product - the online version of Audition. I'm now left in a lurch looking for a replacement for a perfectly functional piece of software. I doubt Adobe would ever fess up to this, but what I experience is very consistent with a kill switch.
Audition let process a couple of files but then started to misbehave again. I uninstalled, reset my system date back to 2021, and re-installed. I became suspicious that some kind of kill-switch was at play. In fact I initially thought it was some incompatibility with Windows 11, so I re-installed on a Win 10 machine with the same behavior. The behavior is one of instability, not inability to install or register. It performes some functions but crashes often (too often to let me do any useful work). My install worked fine until last month (December 2021), then it started becoming unstable.