When creating a Retargeting Audience, you may want to cookie users for only specific period of time. Using the "duration" setting, you can tell Perfect Audience to destroy the cookie from a list after 7 days, or 30 days, or 90 days.
This can be very useful for reaching people at just the right time in their "interest lifecycle" with regards to your business. After 90 days, for example, if a user hasn't visited your site again, they probably won't! Meanwhile, during the first 7 days after a visit is probably when their interest in your product is strongest.
Leaving the duration field empty will set a cookie that remains until the user clears their cookies (90 days max). This can be useful for exclusion pixels (see below).
A note of caution: Using overly short durations on your Retargeting Audiences will make it nigh impossible to reach your audience at a scale that moves the needle for your business. We recommend trying out settings between 30-90 days for longer-scale campaigns alongside campaigns targetking Audiences with shorter, 3-7 day durations to see what converts!