Licenses are for paid plugins, addons and themes. This is normally a once off fee but there are cases where they require an annual subscription. A good practice is to make not of the type of license the plugin, addon or theme has and if it is a recuring license then make a diary entry to remind you to renew this license before it expires. 

If you are not sure what type of license you have please feel free to contact us and we'll assist you with your licenses.