In Odoo ERP you can set expiry date for any product. But what if we failed to notice an expired product and attempt to sell the same? Expiry Date Warning App by team Cybrosys solve the issue by generating a warning message while you try to sell an expired product. This app uses the "End of life date" you set for a product to generate the warning. So first, you need to set an Expiry date for a product.
Read this blog from Cybrosys to know "How to set expiry date for a product".
Blog : https://www.cybrosys.com/blog/how-setup-product-expiry-dates-in-odoo
You can set expiry date from
Inventory --> Inventory Control --> Lots/Serial Numbers
The app generate Expiry warning based on the date you give on "End of Life" field.