The More command
When
a Knight stops an activity, if his Princess says "More" he should
continue with the activity until his Princess asks him to stop.
Devotional
Sex is anything but a Knight only doing what his Princess commands.
Very often what happens will be due to the Knight's initiative, and as
he has not been specifically asked to do something, it is appropriate
that he can initiate the end of the activity.
The More command
makes it very easy for a Princess to enjoy more of a favorite activity
whenever her Knight stops something that she is enjoying. Part of
really feeling like a Princess (rather than just playing the role), is
for it to feel normal and natural for her to say "More" whenever the
whim takes her.
The More command is also particularly beneficial
to Devotees because it also tells her Knight that this is an activity
that she very much enjoys. And as her Knight is wishing to please, this
means he will now want to initiate this activity more often in future
sessions.

Note that the More command can be used not just to
enjoy more of a whole activity (eg more foot massage or more kissing of
her breasts), but more of a specific movement during an activity (eg
more of a particular massage movement during a foot massage, or more of
a particular way of using his mouth while kissing her breast).
An easy and appropriate way of telling her Knight that the More command has ended is just to say "thank you".