A website/app visitor becomes a member of an audience segment when they visit a page/app section containing an ad tag associated with the segment and, optionally, if they match the criteria in the custom key-values passed in the ad tag. Additionally, the visitor must meet the recency, frequency, and membership expiration goals you set up for the segment.
The visitor becomes a member of the segment immediately after meeting the criteria for membership. Line items from the segment will start delivering to them after they navigate to a new page or app section. If a certain amount of time passes without enough new page views or app activities, the visitor's membership expires and they are no longer a member of the segment.
Example
You can define a sports segment that requires a user to view a tagged sports page or app section 5 times within 3 days to become a member of the segment. Every time a user visits a tagged page or app section, the user's membership is re-evaluated according to the page view or app activity and the recency criteria you defined.
If the user doesn't visit a tagged sports page or app section 5 times within 3 days, the user will be removed from that segment.
If the user still doesn't meet the membership criteria, they are removed from that segment. Otherwise, the user can remain in a segment indefinitely, as long as they keep visiting and meeting the publisher's segment requirements and don't delete or reset their identifier (cookie, mobile advertising ID [AdID or IDFA], or PPID) or opt out of interest-based advertising.
If you set a membership expiration of 10 days, a user's membership expires when the user views a tagged page or app section again after 10 days and no longer meets the membership criteria.
A user doesn't need to view a page or app section every single day within the recency period to become or remain a member of a segment.
Example
If a segment requires 3 page views or app activities within 7 days, a user could gain membership by viewing the tagged page/app section 3 times on the first day.
It might take up to three hours for you to see changes to segment membership reflected in your reporting data.