I have a sinking feeling it will not
Well, it still works (sort of) in Win 10, though I've not needed to open it for quite some time, so I see no obvious reason why it would not work in Win 8.
What do you mean "Sort of"?? I have been told that AU 3.0 will not work in win 10 at all, I will need to purchase a monthly 20.99 deal to use AU now 3.0 is no longer useable anywhere but where I have it now when my operating system
Dies and I have to upgrade it will not work in the new system
It works fine on my win10 PC, though I never tried it on Win8 - I missed that "upgrade" step out.
AA3 does work in W10 after a fashion, but I wouldn't rely on it. Your biggest problem if you 'upgrade' your OS from a relatively stable W7 to W8* is that you'd have to have the unlocked version of AA3 available - you can't reinstall the copy you would have purchased.
*W8 came out of support on Jan 10th this year.