Without a plan you can browse the marketplace, request quotes, install both extensions, and use tasks and flows.
A plan raises the daily limit on AI-assisted requests from the editor extension and unlocks the features that depend on them. Your usage chart on the dashboard shows what you have used against that limit.
How usage is counted. The extension reports a count of AI requests to your account — a number, not the content of the requests. That is what draws the chart and enforces the limit. Signed out, nothing is reported and the limit does not apply, because the features that consume it are not available.
Marketplace payments are separate. Paying a seller is not part of a plan; the two are billed independently.
Changing or cancelling takes effect from the end of the current period, and your data is not deleted when a plan lapses.