When you create a tag, you can set expiration options in the tag details tab:
If set to expire, Pathfinder will automatically remove the tag from a contact once the expiration limit is met.
Tags can be set to expire on a specified date, or a number of days after the tag has been set. Note that if expiration time is set in days, the clock will begin from the moment the tag is set for a specific contact.
There are various circumstances where you may wish to use tag expiration, but the most common use case is to track time outside campaigns.
For example, the new contact tag automatically indicates a contact is not already a customer AND has been in Pathfinder for less than 14 days. This is achieved by setting the tag to any contact who is not a customer, and using tag expiration to remove it after 14 days.
Cart recovery campaigns
Pathfinder also uses expiring tags to add cooldown periods on advanced versions of the Cart Recovery campaign. This article explains how these tags work and how to customize them.