Hello @Jo. M.,
My name is Alejandra and I am happy to assist with your inquiry, and appreciate you contacting LastPass Support!
In the case that your LastPass families subscription expires, your family member will continue being part of the families account until you remove them but they will become free users. If you want to reactivate later the subscription, you can do it at any moment and if you want to do it outside the family you will need to get remove from the family and upgrade. To follow the remove family members process you can follow the steps here.
If you need anything else, let me know.
Thank you,
Alejandra
LastPass Technical Support
Thank you Alejandra 👍