I paid for a NASA membership a few years ago and never got my membership.... I wrote to them several times about it, but never got anything back.

It is an insurance regulation anyway, nothing that is done by NASA. The idea of the insurance company is that someone is less likely to make a frivilous lawsuit against an organization they are a member of. It sort also implies that you are partially responsible for how the organization is being run, so if something happens because of neglegence, then you are actually partially responsible.