WordPress makes it easy to upload files to your site. In certain cases, you may want to restrict access to some of those files. The WP File Access Manager can help. It is a handy plugin that lets you control who can access files that you have uploaded. It is especially useful for paid membership sites.
This plugin can bulk protect files by type. It lets you enable/restrict access by user role, login status or for a single user. Thanks to this plugin, you can set restrictions for individual files. It works with PDF Viewer, so you can restrict PDF files in addition to videos, audio files, and photos.