If you want to enable Google (DoubleClick) display advertising on your site, go to WebStore Manager then select Marketing from the top Menu and select SEO. Near the end of the page, you will see:
Update Your Analytics Tracking Code to Support Display Advertising
Tick the Box and your setting will be saved.
This option allows you to support Display Advertising, for example to enable Remarketing with Google Analytics or Google Display Network (GDN) Impression Reporting. If enabled, Google Analytics collects the information it normally does, as well as the DoubleClick cookie when that cookie is present.