You can create weekly and monthly rates by going to Settings -> Pricing -> Longer stay pricing. Those rates will only be displayed if the search dates match whole weeks or whole months.
Months are considered complete if the check-in and check-out date fall on the same day of the month, for example March 3rd to April 3rd, or if the length of stay is divisible by 30.
Note: If you add/remove full weeks/months via the room type edit button within a booking, click “Get price for current dates and number of guests” before clicking “SAVE.” Otherwise, prices won’t be updated.