I want to add a free month to a customer's existing monthly subscription. The obvious choice is to extend the length of the Subscription End date under their current active monthly payment. I'm confused, though: the Subscription End field under Edit Payment says, "This date reserved to internally represent end of recurring subscription (that we does not known yet)." I don't want to mess anything up and interrupt the recurring billing, but I don't see any other way to add a free month. Help?
It is impossible to add a free month to recurring subscription (specially because billing in your case is controlled internally by payment system, and not by aMember).