Microsoft has announced that Office apps are free for devices under 10 inches. Ref - Article on pcworld.com.
Now however Office apps on my Windows 10 mobile(screen size 5inches) is asking for Office 365 subscription occationally. This does not happen always. It happens like once or twice in a week. But it prevents creating or editing docs making office useless in times needed. The screenshot is as follows:
This however is not happening in Office apps in Android. How to stop this? This has caused me much trouble recently. As Windows mobile does not have other famous office suits it seems to be a problem during needed times.