The license type is submitted along with each resource on FlashKit, ie: Freeware, Linkware or Sharware and all resources are royalty free for your use, but all rights remain with the author. Its always my recommendation and my practice, to double check with the author, or at least make the attempt to do so using the contact information provided with each resource when you plan on using those resources in your project. That's being due-diligent and would stand-up in most US courts.