Office on the iPad Pro will require an Office 365 subscription for any and all editing. That’s because Microsoft defines a 10.1 inch cutoff. Anything below 10.1 inches is a “true mobile device” and as such qualifies for free access to the core editing capabilities. But above that threshold and it’s not a “true mobile device” any longer, it’s something else entirely, and it will need an Office 365 subscription as a result …
The 10.1-inch cutoff appears in the licensing terms for both Windows and Android devices, but not yet for iOS – presumably because Microsoft was a little slow to respond to the announcement of the iPad Pro.
The company has not yet revealed exactly what will happen when an iPad Pro user attempts to run the apps.