Family members won’t need a Stadia Pro plan to play games you’ve claimed with your subscription. However, if you cancel your Stadia Pro membership, they’ll lose access to those games as well.
Meanwhile, if a title’s content rating is above the level a family group manager has approved for them, supervised group members won’t be able to play that shared game. Younger members of the group might be automatically locked out of the Mature-rated Cyberpunk 2077, for instance.
Android Police first spotted the family sharing option and Google confirmed its arrival on Reddit. Google is rolling out the feature gradually, and it’ll take a week or so before it’s live for all Stadia users.