Minimum number of nights

First, make sure the "Restrictions" box is checked in the Rates module:



Then you can click on "minimum number of nights" on the left under the room type name:

minimum nights

set minimum number of nights:

minimum nights set

Discount for longer stay?

Another option to take into account higher costs for a short stay is to set a higher base price and, for example, a 10% discount for a longer stay