You can set a custom expiration date for the chat realm here if you wish. Chat instances will be deactivated after the expiration, and deleted permanently within 2 months from the expiration. Chat owner(s) will be sent a notice and a link for extension 2 weeks prior to the expiration
Course chat realms
Course chat realms expire, at latest, after a year from the beginning of the course period. It is possible to lengthen this by 3 months if needed. Further extensions are not currently possible (we cannot store student chat messages and personal data in Zulip indefinitely).