Create a Magento extension that will only allow a customer to login until a given expiry time

czetsuya's tech ― Long time ago I was assigned to modify magento, add an expiry date and check if the costumer is expired during login. Those times resource were scarce and what I did was hacked magento, add custom codes and fields in the database. Which is not a good idea since all the work you did will be washed away if you decided to update your magento installation.So here I am again face with the same problem, but this time we have the concept of community extension in magento /app/code/community, so I'll[...]