The Fall Off panel allows you to easily see the items that have not been purchased in the current "Ship To" customer's ordering history.

 

The top of this screen displays a slider bar that controls how far back to show items the customer is no longer purchasing from you.

Click and drag the slider bar which increments one week at a time.

You can select to display fall off items starting from the current order, one week, and then extending back to twelve weeks.