The rental period for a Redbox movie rental is one day which starts from the time you rent the movie until the next day at the same time and the redbox movie rental must be returned to the Kiosk by 9:00 PM the next day or you'll be charged for another days rental of the movie.
So if you only want to pay for one days rental on the Redbox movie then be sure to return the movie to the Kiosk by 9:00 PM the next day.