Item Licences?

hi just want to ask, when i go to edit i see a option called item licences what is that can anyone explain this better? it just says

Choose the licences that your items are sold under. Note that not all licences will be used for all types of items. The Standard Single-Use Licence is mandatory.

shouuld i check the button : Extended License ??

http://wiki.envato.com/selling/author-selling/opting-in-to-the-extended-license/

http://wiki.envato.com/selling/author-selling/opting-in-to-the-extended-license/

thanks,