An expiry notification or indication on Excel generally pertains to dates. Herein, dates that have expired or are close to the date of expiration may be highlighted, and you can do so using the conditional formatting option in Excel. Click on Home > Conditional Formatting > Manage Rules > New Rule. Here, select ‘Format only cells that contain’, ‘Less than’ from the second drop-down and enter the following formula:
=NOW()+30
Save this and you’ll notice all the expired dates having been highlighted.