Every invitation code you generate is shown as Available, Used, Revoked, or Expired.
Available means nobody has claimed it yet, so you can still share it, copy the link, or revoke it. Used means the first successful sign-up claimed it, and the list shows who used it and when.
Revoked means you cancelled the invitation yourself, so it can no longer be claimed. Expired means its date passed before anyone used it.
One code works for one account only. If two people receive the same code, the first successful sign-up claims it, and the second person needs a new invitation.
