Final answer:
A remarketing audience must adhere to Gogle's advertising policies, have a minimum of 1,000 cookies, and be associated with the advertiser's active campaign or ad group in an adwords account to be eligible for search ad marketing.
Step-by-step explanation:
To make a remarketing audience eligible for search ad marketing in an adwords account, there are specific criteria that need to be met. Firstly, the remarketing list must comply with Gogle's advertising policies. This includes user privacy requirements, where users are made aware of the data collection for remarketing and can opt-out if they choose.
Additionally, there is a minimum size requirement for the audience list. For remarketing on the Search Network, the audience list must contain at least 1,000 cookies before the list can be used to tailor your search ads. This ensures that the audience has enough members to maintain the anonymity of the individuals in the list.
Lastly, the remarketing list must be associated with your adwords campaign or ad group that you intend to use for search ad marketing. The audience list must be created in your Gogle Ads account (formerly known as AdWords) and should be linked to a campaign that is actively bidding on keywords relevant to the remarketing audience you wish to reach.