By not suddenly closing access to the app to any but users of Office 365 for Business, with no warning.
I've used OWA on my iPad for a couple of years, with great success and satisfaction. Suddenly, 48 hours ago, I can no longer access it... Probably because I don't have "the latest version of Office 365 for Business". Explanation/Solution, please? I have no intention of getting ANY version of Office 365.