To print the expiration date on your product labels, you first have to turn the feature on by enabling it either from the List & Prep page or the actual Print Settings page.
This can be toggled on or off on the List & Prep page by clicking Print Settings near Open Batches
Scroll to the bottom of the page and you will see the Include Expiration Date option. Click the toggle to the right of this option to enable/disable it
Once enabled, you can print the Expiration Date on your labels!