if ( ! function_exists( 'x_excerpt_string' ) ) :
  function x_excerpt_string( $more ) {
    if (is_user_logged_in()) {
      return '  <div><a href="' . get_permalink() . '" class="more-link">' . __( 'Read More', '__x__' ) . '</a></div>';
    }
    else {
      return '<div><a class="more-link" href="' . wp_login_url(get_permalink()) . '">Log in to read more</a></div>';
    }
  }
  add_filter( 'excerpt_more', 'x_excerpt_string' );
endif;

if (is_user_logged_in()) {
    query_posts( 'orderby=rand&posts_per_page=1&post_type=card&cat=9' );
    }
else {
    query_posts( 'orderby=rand&posts_per_page=1&post_type=card&cat=8' );
}

<?php if (!is_user_logged_in()) { echo '
<p>To get access to the whole card deck along with follow-up exercices, please <a href="' . wp_login_url(get_permalink()) . '">log in.</a> If you are not a member, <a href="/members">register for free</a>.'; } ?>