A subscription is for a single person. For example, for a couple, partner 1 and partner 2 each is to purchase a separate, single subscription. For a parent and child (old enough to want to enjoy the websites) each is to purchase a separate, single subscription.
The purchase of subscriptions is entrusted to you to manage on the honor system.
Honor is at the core of civilization. Honor is at the core of the purposes of the websites.