Hi
it's about IRM
check this similar post
https://social.technet.microsoft.com/Forums/ro-RO/03f2a503-1042-447e-8f27-33ed8887a83d/how-to-restrict-document-download-in-sharepoint-2010?forum=sharepointgeneralprevious
Romeo Donca, Orange Romania (MCSE, MCITP, CCNA) Please Mark As Answer if my post solves your problem or Vote As Helpful if the post has been helpful for you.