It adds a meta box to the post or page edit screen and lets the user select specific users by name or roles and then when you call that page content using “the_content();” function it check using “the_content” filter if the current user is one of the users you have selected or if his role match’s the roles you have selected and shows the content, otherwise it displays a message.
https://wordpress.org/plugins/user-specific-content/
similar - http://codecanyon.net/item/privatecontent-multilevel-content-plugin/1467885
https://wordpress.org/plugins/user-specific-content/
similar - http://codecanyon.net/item/privatecontent-multilevel-content-plugin/1467885