Free accounts can have up to 2 active (editable) pilots. If you downgrade — or a Pro subscription lapses — while you have more than 2 real (non-sample) projects, you’ll be asked to pick which ones stay active. The rest switch to read-only: still visible, still exportable, just not editable or shareable until you make room or upgrade again.
Nothing is deleted. You can revisit this choice anytime from the dashboard, and re-upgrading to Pro immediately makes every pilot active again regardless of what you’d picked.