If you have a family sharing plan on your iPhone, you know you can download apps that other family members have downloaded, but you could not share in-app purchases in those apps. Until now! Apple has confirmed that it will now allow for in-app purchase sharing with family members.
This is for things that need to be unlocked with payments, such as subscriptions, upsells, games. These things can be shared with up to 5 people in a family. To turn this on, go to the Settings section of the App Store, and look for the “Share New Subscriptions” feature.