// filter the product title
add_filter( 'the_title', 'wtl_shorten_my_product_title', 10, 2 );

// limit product title on shop and category page
function wtl_shorten_my_product_title( $title, $id ) {
    $option = get_option('wtl_opt');
    if(is_plugin_active('woocommerce/woocommerce.php')){
        if ( is_product_category() || is_shop() && get_post_type( $id ) === 'product' ) {
            return substr( $title, 0, $option['wtl_count'] );
        } else {
            return $title;
        }
    }else {
        return $title;
    }
}