No solution for previous office suit(premium) paid version buyers.
This app with full premium functionality was a 19.99$ app, which they just vanished from the app store without giving any update to previous paid users and turn that into this inapp purchase version. Although that paid version is still downloadable from "purchased app" category, but that one doesnt support ios 10. Now, does previous owner have to pay you twice for the same app? Hope app developers make that paid version online again with support.
The app was really a very good alternative to subscription demanding Microsoft office in ios store & my favorite as office app.
Castor roy about
OfficeSuite - Office Editor, v5.4.1