book up

verb

To reserve or book all of something, for example by purchasing all the tickets.
To have all of its tickets or reservations purchased.
“Flights are beginning to book up as people flee the region.”
To study opening lines in great detail in order to gain an advantage.
“There would be more extraordinary clock goings on in the big game of the day, Aronian-Firouzja, which began by giving a partial answer to the question of what Alireza Firouzja had been doing for the last five months. He’d been booking up on some old theory!”
To study or learn (something).