Automatic & free -backup on selectable cloud /local drive is necessary
one of The features which is very important is : This kind of Applications must have the automatic backup not manually,
because when we trust to this application to write or notes it's going to be very important and everybody Maybe worry of his documents lost.
So I think the automatically backup is one of the most necessary features which must be free installed on your application.
And As you know there are many users who can't or don't purchase the Premium by any reason but this is a -fundamental & Necessary feature which can make your APP trustable and if not ;it would be very dangerous to use it Commonly & generally as the defult note book instead of paper one !
Also I need to emphasize on the word "selectable" =favorite cloud! Not only something like Google drive or one note. Because for example I use some Chinese cloud as like as Baidu. 盘
Or QQ CLOUD.
so the user must have the option to choose from his device's clouds optionally