There is no universal expiration time for temporary email. Some services remove an inbox after a short period, while others keep it active until a period of inactivity. The website administrator can configure the provider used by QuickTemp Mail, so users should check the service information displayed on the site. If an account matters, do not rely on a temporary inbox for future access.
For practical use, always review the provider rules and avoid sharing sensitive information through temporary inboxes. A temporary address is best suited to low-risk, short-term interactions.