Create a remarketing campaign in Campaign Manager
Create a remarketing campaign in Display & Video 360
Before you can launch a remarketing campaign, you must create an audience list in Campaign Manager or Display & Video 360 to set up a targeting strategy and associate it with a website. Without a targeting strategy, users will get targeted with dynamic remarketing creatives even though they haven't taken any action on the actual website, resulting in either default content from the default rows of your feed, or default ads to be shown.
1. Use the same lifespan for audience list and cookie
The lifespan of the audience list should be the same as the lifespan of the cookie associated with the custom variable used for remarketing (set up in your Studio Remarketing attribute). For example, if you're targeting users with product information for 30 days, the audience list should not be older than 30 days. However, you can set up additional line items to target different time periods, (for example, 7 days, 14 days, or 30 days).