When purchasing Super Sofa, you have the option of subscribing to a family plan. This plan allows you and up to five other people to share your Super Sofa subscription.
For this to work, you need to be using Apple’s Family Sharing. Once you have Family Sharing set up, anyone on your family sharing plan will have access to Super Sofa.
If members of your family are not seeing a Super Sofa subscription, they may need to restore the purchase on their device.