Editing remarketing list membership duration span
Here are three quick Qs about the mechanics behind remarketing list membership duration:
1) f I have a remarketing list running for 100 days with a membership duration set to 30 days and then change it to 60 days. Will anything happen? I.e. is the remarketing cookie set to expired after 30 days or is it still on the users computer so that the 60 day change will have an effect?
2) If I have it on 100 days initially and change it to 60 will the list decrease?
3) If I do 2) and then increase it again, will the list increase?
Re: Editing remarketing list membership duration span
1) Cookies previously set for 30 days will still expire in 30 days. New cookies set with a 60 day duration will expire in 60 days.
2) Eventually the list will decrease if you decrease your cookie duration because new cookies being set will have the shorter duration.
3) Eventually the list will increase again if you decrease the cookie duration then increase it again.
By how much your list size will change depends on how often and/or how frequently you change your cookie length. It also depends on how much traffic you have.
I would suggest that you choose a duration and stick with it for long enough to know if it works for you or not (which could take months). When/if you make a change, you will, again, need to leave that change in place for long enough to know whether or not it's an improvement. (There is no particular harm in changing your cookie duration whenever you want, but there is no benefit to doing so, either.)
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