The question is:
The Apple App store has a feature called Family Sharing. With this you are meant to be able to buy an app once and share it among a family. Will Family Sharing work with LuckGrib?
The short answer is: no. The most important sentence from the image above is that in-app purchases can’t be shared with family members.
LuckGrib uses the in-app purchase process to start the 14 day free trial as well as to purchase the product. As the Apple in-app technology is used for this process, and Apple does not support in-app purchases with Family Sharing, a LuckGrib purchase by one family member does not allow all other members to share the same purchase.
Update Feb 2021.
Apple now allows family sharing to be used with the in-app purchase model used by the app. Support for family sharing may appear in a future update.