While searching for offers, a banner noting the time remaining on the offer will be present over the product image if that offer is expiring within the next seven days.
You will also see the hourglass icon in the Offer Details alerting you the offer is expiring soon.
Once you add an offer to "My Offers," you will then see the specific expiration time listed under the offer's thumbnail on your list - e.g. [Exp. 03/02/19 at 5:00 PM]. You can also look for the red flag wrapped around the thumbnail image with a stopwatch icon alerting you that the offer is expiring soon.
If the Offer Details page is opened from "My Offers," no expiration date will be visible unless the offer is expiring within 7 days, in which case the expiration banner with the remaining time will appear under the product image.