Your account and your data
What you keep
The short version: you keep every thing you wrote, and you keep anything you bought.
If you cancel Plus
Your things are untouched. Every thing, list, day, tag, reminder and photo stays exactly as it is. Nothing is deleted, hidden or held hostage.
Plus features become read-only rather than destructive. A tagged thing keeps its tags and you cannot add more. A sublist stays a sublist. An archived list stays archived. Nothing you built is dismantled.
You can still write. Capture, days, carry-over, reminders and search are all free and continue exactly as before.
Features you bought with coins
Yours permanently. A feature unlocked with coins survives cancelling and is not taken back. See buy a feature a la carte.
This is the clearest commitment in the pricing model and it is worth stating plainly: buying means buying.
Grandfathered features
Some features were free before they were gated, and accounts that predate the change keep them at no cost.
The docs mark these where they apply, and the marker is generated from the app's own entitlement table rather than typed by hand, so it cannot drift out of date.
Examples of features carrying a grandfather date include Universe and bookmark colours. If you have had your account a while, check before paying for something you may already have.
Going further
Nothing degrades over time. There is no gradual lockout and no reduced limit that appears months later.
Export is always available. Whatever your plan, you can take everything out. See export your things.