This reader suspects that the a creature freed from the effect of a scribe's binding spell does not leave behind in the focus book a record of its memories to that point. This is because the first line of the spell's description says that it "binds a single creature into a prepared book, sustaining it in suspended animation and filling the book with its experience and knowledge." That phrase after the comma describes what "binding a… creature into a… book" means; hence, after the creature's freed, the creature's is not "in suspended animation and filling the book with its experience and knowledge."
Thus, this GM would rule that after the creature's freed, the book's emptied of the creature's memories. (By the way, apparently that book, once emptied, can be reused.)
Were this not the case and a creature's memories remained in the book even after the creature's freed from its binding, the book's possessor could continue whimsically manipulating the creature's memories with impunity, the creature never knowing nor being able to resist. While this GM has a thorough and healthy respect for 9th-level spells, this seems a bridge too far. (Of lesser concern, were that the case, then the book couldn't be reused, the creature's memories having "fill[ed] the book.")