1. Go to Settings -> Price changes -> Discount for longer stays.
  2. Discounts can be set for full weeks or months, or for a custom range of days, for example 3-5 days.
  3. Specify the discount for each room type.

Note: Discounts for longer stays are not included in the updates to booking channels (Booking.com, Expedia, etc). Rates are set for individual dates when updates are sent to channels. The booking channel will then sum up the total for the booked dates.