I have never tested out what happens if you remain offline for any period of time, but it is my understanding that once you have activated the program on your machine, you do not need to be constantly connected to the internet. But, you will be periodically asked to sign back into your account. I have no idea how often that might be.
No, it cannot. You sign in to authorize it to be used on your computer. You sign out when you want to deathorize it- and move it to another computer.
You wanna use it? You have to be signed in.
Like Greg said- you will be asked to "sign back in" if your are totally off line, like you're out in the sticks somewhere with zero connectivity. PSE always wants to be able to tell "big brother" that it's being used, and here's the serial number of what's being used. If PSE can't "Phone home" it's gonna tell you "Dude, you have to sign in"..... there are some cases from a few years ago where the software simply loses track of the serial number you entered, so it gets a bit confused.
Not signed in? You won't be able to download any of the graphics you see in the graphics tab (I find them pretty much useless though).
AS AN EXPERIMENT: I also turned off all the adobe background processes just to see what would happen, on a short term basis-- so far it's been about 30 minutes and PSE is working fine, and I remain logged in.
I have to assume that PSE is just like Facebook: It's always pinging home to say "Here I am, I'm still connected and can see you" (facebook does that about once ever 30 seconds- which is a good thing).
Thank you everyone for your great replies. Sadly, I've removed downloaded incident and blocked CC charge. I will just continue using the older version while looking for less intrusive vendor. It's a small petty act but growing privacy violations is an issue to me.
Looking closer at their 2020+ EULA, Adobe now tracks location, device details, search engine to use on-device desktop software for their use and resale. Opt-outs do allow hiding usage and content details from ourselves; slightly different in EU and subject to change. But, any software that tracks real-time a device's MAC address in order to use software has access to all information on that device. As my ISP techs say, 'Yea, we see everything you do, you sick, sick people!'