How don't appear History tab.

there is not easy way as this is a tab task and that one cannot be un/checked in the menu, but the history tab is visible only to "chief editors" and "editor" roles (and to site admin). If you really want to get rid of it, i would recommend changing the ejournal_menu() function

remove it, or add something like: is_numeric("x") inside of the code

    if (is_numeric(arg(1))) {
      if (arg(0) == 'node') {
        $items[] = array('path' => 'node/'. arg(1) .'/ejournal/history',
          'title' => t('History'),
          'callback' => 'ejournal_article_history',
          'callback arguments' => array(arg(1)),
          'access' => ejournal_user_access(array('chief editor', 'editor'), ejournal_journal_get(arg(1))),
          'type' => MENU_LOCAL_TASK,
        );
      }
    }
  }

i can move the logging functionality to separate module in the future, but that is low on the priority list

hi, fixed now - thanks for reporting