Every module except Petsitting gives you the option to track belongings for the pet.
It's on the right click menu on the schedules and calendar.
There is a Belongings button on the left side of the modify appointment screen.
Belongings is also on the right click menu for Arrivals and Departures on the Full Day View.
You can set the option so that the belongings screen pops up on the screen after you check a pet out. That is in File, System Options, under each module tab.
You can print a report for boarding pets to get a list of belongings for pets based on check in/out status and checkout date. Reports, Boarding, Belongings.