An instant meeting ID expires when the instant meeting ends. A non-recurring meeting ID (also known as a one-time meeting ID) will expire 30 days after the scheduled date, if the meeting is not recorded. You can also reuse the same meeting ID within the 30 days to restart a meeting and it will remain valid for another 30 days. A recurring meeting ID expires if it is not used for 365 days.  You can keep using your Personal Meeting ID while your HKU Portal account is active.