Prep & Pantry can automatically default to a location. If you only have one location, Prep & Pantry will use this location by default and you will NOT be prompted for a location.
Another option is to use the 'Remember' setting.
Accessible through Manage Locations or Settings and Options> Remember Last Location; setting this to ON, Prep & Pantry will keep track of the last location you used and automatically enter this location when adding an item to inventory. This is particularly handy when your adding several items to one location.
Changing locations is as simple as selecting a new location from the list.