Hello,
you can't set an expiry date for an Item, you can only close the record manually.
But you can control the sale of Items based on their Best Before Dates.

Controlling the sale of Items based on their Best Before Dates requires the following configuration work:

You can only use Best Before Dates with Items that have Serial Numbers at the unit or batch level.
Each Best Before Date will be connected to an individual unit or batch Serial Number.
The first step is therefore to ensure that you have specified in the Item register that each Item requiring Best Before Dates is a Serial Numbered Item.

An Item/Serial Number with a Best Before Date might have a life cycle with several stages.
In an example life cycle with three stages, you will at first be able to sell the Serial Number freely As the Best Before Date approaches, you may wish to be warned about this when you sell the Serial Number.
When the Best Before Date has passed, you should be prevented from selling the Serial Number.
For each stage, you should assign a status to the Serial Number that will determine whether it can be sold and if so whether a warning will be shown.
Use the Batch Status setting in the Service Orders module to define these statuses.

When you deliver or sell an Item with a Serial Number, you may use 'Paste Special' to choose the Serial Number.
If you would like the Best Before Date and or Batch Status of each Serial Number to be shown in the 'Paste Special' list, select the Show Best Before Dates and/or Show Batch Status options respectively in the Item Settings setting in the Sales Ledger.