iCloud Family Sharing is a feature from Apple that allows you to share eligible in-app purchases and subscriptions with your family members. Once you have activated family sharing on your iCloud account and invited your family members, they will be able to also use your Structured Pro subscription at no additional cost.
To enable family sharing for Structured, select your name in the Settings app and tap Family Sharing. After you have invited your family members, you can enable Structured Pro under Subscriptions to share it with your family members.
It might take a couple of hours for the subscription to be enabled for other family members and they might need to hit the Restore Purchase button on the paywall.
If you still cannot use Family Sharing for Structured after following these steps, please contact the customer support.