If you have an active subscription to Pillow's premium features, then you may share them with your family. To share your subscription using Family Sharing please ensure that all of the following is correctly set up:
Purchase sharing is enabled on your device.
Your family members are allowed to share purchases you make on the App Store.
See instructions here: https://support.apple.com/en-us/HT201454Pillow is not hidden from your purchase history. See instructions here: https://support.apple.com/en-us/HT201322