Will I lose my cookbooks or data when the Family Plan expires?

No — everything you've created stays. Your account, cookbooks, every recipe you've written or scanned, every photo and audio memory, all your notes and ratings. The only thing that changes is your plan tier: free-tier limits apply to new recipes until you re-subscribe. Think of it like going from premium Spotify back to free Spotify — your playlists are still there, you just can't add unlimited new ones.