From AppleInsider.com…..
You’ve long been able to buy an app once and have your entire family use it, but now Apple’s brought that to some subscriptions — although with similar limitations and exceptions.
As announced back in June, and finally going live in early December, Apple has introduced the ability to share your subscriptions with your family. It’s taken some time to roll out to all users, but it’s now available to everyone — with a certain limitation.