30% cut of people that subscribe to office 365 through the app (which Apple requires be an option, MS can't force you to go to their site to subscribe or Apple kicks them off the store, see the epic vs apple lawsuit: https://en.m.wikipedia.org/wiki/Epic_Games_v._Apple )
Unlock the full Microsoft 365 experience with a qualifying Microsoft 365 subscription for your phone, tablet, PC and Mac.
Monthly Microsoft 365 subscriptions purchased from the app will be charged to your App Store account and will automatically renew within 24 hours prior to the end of the current subscription period unless auto-renewal is disabled beforehand. You can manage your subscriptions in your App Store account settings."