Hello @Jamie Connell,
My name is Henry and I am happy to assist with your inquiry, and appreciate you contacting LastPass Support!
If those passwords were shared via a Shared Folder, you should continue being able to access to them indefinitely.
However, if those passwords were shared individually then you may lose access to them once the sharing key expires or becomes corrupted, if this is the case I would suggest to clone those passwords to store them locally in your vault.
Thank you,
Henry | Customer Care