Importing Existing Subscriptions
To import existing subscription customers into s2Member, you can include the Subscription ID in the member's profile, so that s2Member can receive future communication about these members from PayPal's IPN service.
So, if you include the Paid Subscr. ID value when you do the import, and your PayPal IPN URL is reporting properly to your installation of s2Member (WP Admin -> s2Member -> PayPal Options -> IPN), s2Member can automate the management of these paying customers.
This includes any associated payments, cancellations, refunds, chargebacks, etc. If s2Member has the Paid Subscr. ID value, and PayPal is sending s2Member IPNs, these events can be handled by s2Member, including any EOT (End Of Term) events.
Now, in practice this is not always easy to accomplish. For instance, if your previous membership software used the PayPal Button integration and an IPN URL was established on a transaction basis, it might not be possible to update the IPN URL for each of your existing Members before importing them into s2Member (PayPal has some limitations in this regard).
Another issue is that s2Member expects to receive IPN data with the PayPal "custom" value set to your installation domain name, and with a proper item_number value, matching s2Member's standardization. Further details on this in your Dashboard under: WP Admin -> s2Member -> PayPal Options -> IPN.
In cases where these technical challenges get in the way of a smooth migration, we recommend that you import your existing userbase with a pre-configured EOT Time. Setting the EOT Time during your import will ensure that s2Member terminates each Member's access at the correct point in time, based on the data in your import, and without any reliance on existing IPN communication, which might have previously been configured to work with an entirely different software application.
Setting an EOT Time when importing Users/Members from software applications you used prior to running s2Member, is a very reliable way to deal with things. It leaves little doubt about how s2Member and any existing IPN data might be handled in the future. A pre-configured EOT Time establishes the exact date on which a Member's account will lose paid access. After import, this value can also be changed by editing the user's profile from WP Admin.