A license key is necessary to obtain the automatic updates and to access to the helpdesk support.
A license key is valid for one year as from the date of purchase. It may be renewed after one year at a preferential rate (currently 50% of the new license price). If a key is not renewed prior to its expiration, the plugin will continue to operate but you will no longer have access to automatic updates and helpdesk support.
It is recommended to run the latest version of WordPress, your theme and your plugins.