Microsoft Invest - Set line item frequency and recency caps
You can cap the number of times (frequency) and how often (recency) creatives can be shown to a given user.
Frequency caps can be set at the line item, advertiser, insertion order, and creative levels, or any combination of the four levels. The most restrictive setting always takes precedence.
See Frequency and Recency Caps for more information about understanding and configuring frequency and recency.