Wiktionary
keep in
vb. 1 (&lit keep in English) 2 To require a pupil to stay after school as a punishment. 3 to stay blazing (of a fire) 4 To cause (a fire) to stay blazing
WordNet
keep in
v. cause to stay indoors
Usage examples of "keep in".
And all the time he tried to keep in his mind the image of her dancing the leading role in Daphnis and Chloe, the black and white shot of the impossibly high arabesque that he kept on the chest of drawers in his bedroom, because then he could almost forgive her.