Membership duration bound to user list or to ad?

[alexande...@emarsys.com]

Dear AdWords API Team and fellow devs,

what I got from the docs so far:

Membership duration is the number of days a user's cookie stays on your remarketing list.

How it works: When you create a remarketing list, you decide how long a visitor's cookie stays on your list if that person doesn't visit your site again.

Can you please comment on my educated guesses:
Membership duration for a visitor depends on the site of the ad. If he visits the site within the membership duration he stays on the list. This is tracked via Google search or a Google pixel added to the site.
The members in the user lists stay the same because whether somebody is in/out is tracked via the ad associated with a site. Therefore when creating a new campaign with ad group and ad the whole user list is used.
When a user is added to the user list via the API after ad creation the membership duration starts at that very moment.
Best,
Alex

[Yin Niu]

Hi Alex, 

Let me try my best to answer your questions. 

List membership is managed by cookies. The member duration is how long you’d like to store a cookie in someone’s computer and target him or her. 

• Membership duration decides how long before the cookie expires. If you set duration to 30 days, the cookie will expire in 30 days. The visitor's cookie is deleted from the list at the end of the duration if there's no new activity. If the person visits your site again, the clock is reset for another 30 days or for the duration you've set. 
• The members in the remarketing list will vary when cookie expires or if the users deleted the cookies by themselves by clearing up the browser or when new cookie is collected. 
• Membership duration starts when the user visits the site and the cookie is collected. 

If you have more questions regarding remarketing list membership, please post them on AdWords forum. 

Thanks, 

Yin, AdWords API Team.