The easiest way to accomplish this is to use the update profile property action functionality using a flow. To start, create a flow triggered by someone being added to each list in your account. Once you have created the flow trigger, add in an Updated Profile Property action. You can create a profile property called List Membership and then assign a value of the list name.
For more information on how to do this, head to this article on the Update Profile Property action.
Your next step is to back-populate the flow. Choose the second option to schedule emails relative to when I hit the back-populate button.
As long as you only add the update profile property action to your flow, no messages will send out because your flow does not contain any emails or SMS. Instead, this will send all of the customers in your list through the flow to add the custom property to their user profiles in Klaviyo.
You then have two options to export these profiles and know what list they are a part of:
- You can create segments of customers using that property and each of it’s values; then, export the segments (by clicking into the segment and selecting Manage Segment > Export Segment to CSV).
- You can export your individual lists (by clicking into the list and selecting Manage List > Export List to CSV) and see which lists your customers are a part of by looking at the custom property values associated with their profiles.