How to add a new endpoint in woocommerce

seems woocommerce doesn’t have any filters when registering their endpoints,
https://github.com/woothemes/woocommerce/blob/master/includes/class-wc-query.php#L84

so you need to add your new endpoint on init hooks, just like this

add_action( 'init', 'add_endpoint' );
function add_endpoint(){
    add_rewrite_endpoint( 'license', EP_ROOT | EP_PAGES );
}

then you have to do some filtering on wc_get_template to call your files when the request match your endpoint

add_filter( 'wc_get_template', 'custom_endpoint', 10, 5 );
function custom_endpoint($located, $template_name, $args, $template_path, $default_path){

    if( $template_name == 'myaccount/my-account.php' ){
        global $wp_query;
        if(isset($wp_query->query['license'])){
            $located = get_template_directory() . '/your-path-to-file.php';
        }
    }

    return $located;
}

so when you visit my account page with endpoint license,
let say http://yourdomain.com/my-account/license/, that will display your custom code