Tap Restore Purchase on the payment page to unlock access for all active subscribers and their family members via Family Sharing.
If your subscription has expired, the restore will not work. You can check your subscription expiration date on the payment page.
Make sure you are signed in to the same Apple account that was used for the original purchase. If you are not sure which account that is, look for the email receipt from Apple — it will show the Apple account used for the transaction.