How can we prevent users using their accounts after leaving the organisation?

Expiry dates ensure that users will not be able to use their accounts after leaving until these have been deleted. It is the site's responsibility to find out about students who do not finish their course, or who take time out in the middle of it. The expiry date facility may be used to temporarily suspend an account during extended absence, the account can be re-activated when the user returns by altering the expiry date.