Summary: At this time, there is no set limit to the number of impressions you choose to display using Amazon Mobile Ads. It is recommended, however, that you limit this number by either using your own integration of selective targeting, or setting your frequency rate when creating a new promotion. This will provide your other ad services (including standard Amazon Mobile Ads keys) opportunities to successfully fill after this frequency cap is hit.
We recommend that you cap the frequency at 2 impressions per day per product promotion. By setting a lower daily or weekly frequency cap when creating new promotions, you'll be allowed to further balance impression exposure when having multiple product promotions tied to one single app key.