An advertiser wants to make sure that people on Pinterest who have purchased its product no longer see its ads. What should the advertiser do?

To prevent ads from being shown to existing customers, the advertiser should exclude the "checkout event audience." This audience segment is automatically populated with users who have completed a purchase on the advertiser's website, based on data from the Pinterest tag. By excluding this audience, the advertiser ensures that their ads are not wasted on individuals who have already converted, allowing them to focus their budget on acquiring new customers. Including additional keywords or narrowing interest targeting would not prevent ads from being shown to past purchasers. Excluding an actalike audience would prevent ads from being shown to users similar to existing customers, which is not the goal here.