Continuum is one of the most appealing new features in Windows 10 Mobile, allowing users to effectively turn their high-end handsets into mini-PCs, by connecting them to a larger monitor or TV, and interacting with them via a mouse and keyboard, complete with a PC-style user interface and Start menu.

Virtually all of Microsoft's demos of Continuum on Windows 10 Mobile have showcased the ability to create and edit Office documents using the PC-style mode - but as it turns out, that functionality won't be free for everyone indefinitely.

In a post on the Office blog today, Microsoft highlighted the value of its Office Mobile apps coming pre-installed on its new Windows 10 Mobile handsets, reiterating that "you can even use the Office apps on your phone like a PC with Office support for Continuum."

But further down that post, it elaborates further:

Office Mobile + Continuum—Continuum is a new Windows 10 feature that allows you to use your phone like a PC. When you connect your phone to a larger screen, keyboard and mouse, your Office Mobile apps scale up so you can work on Office documents like you would on a PC*. While using Office on a larger screen, you can continue to use your phone and other mobile apps separately for multitasking.

That asterisk in the excerpt is particularly significant, pointing to this little detail:

*Editing in Word, Excel and PowerPoint with Continuum for phones will require an Office 365 subscription, but is available to try without Office 365 through March 31, 2016.

This is certainly news to us here at Neowin - and from chatting to a few well-informed journos on the Microsoft beat, it raised eyebrows among them too. That said, it does line up with Microsoft's policy of requiring an Office 365 subscription to edit Office documents on Windows devices larger than 10-inches, even with its free Office Mobile apps.

Nonetheless, it seems clear that the functionality that Microsoft has been showing off as a key selling point of its new phones will require an additional Office 365 subscription to be able to take full advantage of it after the initial 'trial' period ends on March 31, 2016.

It's worth pointing out that Microsoft does state in the footnotes on its Store pages for its new Lumia flagships and the Display Dock: "Office 365 subscription required for some Office features". However, the limitation of only being able to edit Office files in Continuum mode without further payment until March 2016 is not explicitly clarified anywhere on those pages.