Sorry for hijacking this thread, but I'm hoping someone can help me out...
I downloaded Office 365 from the Apple App Store about 3 weeks ago and am currently under their "free month trial". A few days later, I found a deal on a deal website for a discounted 1-year subscription to Office 365 Home (same version I'm under the trial for). I purchased that and received a box in the mail with the key code for that, but haven't opened the box. It later occurred to me that if I log into the Microsoft site and enter my key code (assuming it will even let me), that this info might not flow down to Apple properly, and Apple might bill me for a year's subscription when my monthly trial ends.
I'm thinking that the safest course of action is probably to cancel my subscription through Apple and then go to the Microsoft site to make use of my key code. As with the OP, I originally thought it would be a good idea to get it through the App Store so as to let Apple handle the auto-updates. I'm guessing that there may not be a way to have my subscription managed through Apple while still being able to take advantage of discounted annual subscription offers.
Anyone have any experience/thoughts on this?