The expiration dates printed on sponsored Priority Pass cards do not extend the life of the membership past the point where the sponsor (e.g. Citi) notifies Priority Pass that you are no longer eligible. You will receive a letter from Priority Pass inviting you to purchase a membership.
I think one is eligible for
standard PP membership until the expiration date of the PP card without paying PP annual fee ($99 otherwise). One just has to pay $27 per person per visit.