WPDM Block Hotlink add-on will help you to block hot link to download URL from external site. You must have to click on download button placed in your site to download packages. External site can only place the link with your page.
Download WP Download Manager Block Hotlink 2.1.1 at WP Liga for Free with an active Membership. You will receive the exact same .zip file distributed by the original author, secure and 100% virus free.