No, it’s not possible to share Todoist Premium via Apple’s Family Sharing or Google’s Family Library. This is because the subscription is considered an in-app purchase.
Q: Is it possible to pay for all my family members from one account?
A: Yes, if you sign up for Todoist Business you can invite your family members to your Business team. Then, as the admin of the team, you will be billed for all its members.
Q: Is it possible to get a discount for my family members?