Bloquear acesso para não assinantes/não admins

<?php
if ( have_posts() ) : while ( have_posts() ) : the_post();
    $private = get_post_custom_values("private");
    if (isset($private[0]) && $private == "true") {

        if ( current_user_can( 'administrator' ) ) {
        the_title();
        the_content();
        } else if ( current_user_can( 'subscriber' ) )  {
                the_title();
                the_content();
               } else  {            // text to show instead the post
                    echo 'this post is private';
        }


    } else {        // this is visible to all
        the_title();
        the_content();
    }

endwhile;
endif;
?>