I just registered in order to complete this questionaire
Yep, I use Windows 7. I've used Windows 10 and it's a turd. If I move on it will likely be Linux, but I'm not yet at that stage. Of course, things are starting to not be compatible, although VxKex sorts out quite a few.
I use Sandboxie mainly for two things:
1. Try stuff out without having to do backup/restore or mess with a VM (which wouldn't be close to my actual setup anyway).
2. Force apps to go where they don't want. For instance, my system drive holds only critical apps (that is, those necessary to boot the PC) so it's quick and easy to backup/restore. So why on Earth does Garmin want 15GB of it to dump a map I'm not interested it? With Sandboxie I can force that off to a more appropriate drive, leaving my system drive in peace.
3. (Because I can't count) The ability to run apps with different configs. Again using Garmin as an example, I have personal satnavs but also support a charity's vehicle satnavs. I don't want my configuration settings to pollute the charity's satnavs (different vehicle types for a start) so I use Sandboxie to force different configs depending on whose satnavs I'm dealing with.
I accept that recent apps are likely not to work, and with apps that just fail because they need a W10 feature that's not here, I have no problem. I am not expecting support for them. What I really hate with a passion is those apps where the developer has actively stopped them even starting up because they don't want me to use W7 or something. Let it try, please, and it if works it works while if it doesn't.. well, too bad.
So, I would like to keep updating Sandboxie because it's a great util (and I've been a user for a looong time - just never needed to get onto a forum or support). But I accept that keeping it supporting an obsolete OS is harder to do, and at some point you have to decide to move on. Sandboxie will still work as it is now, we just won't get any new features. Much as I'd like to continue getting updates (and paying the fee!) I'm not going to hold it against you if that doesn't happen. It's been a great ride and still is.