TranslatePress Set Language To Cookie

translatepress-language-cookie.php

<?php
/*
Plugin Name: TranslatePress Language Cookie
Description: Set the current language from TranslatePress in a cookie 
Version: 1.0
Author: ashweb
Author URI: https://www.ashwebstudio.com
*/
add_filter( 'init', 'aws_set_language_cookie', 999 );
function aws_set_language_cookie() {
    global $TRP_LANGUAGE;
    if ( isset( $TRP_LANGUAGE ) ) {
        $result = setcookie( 'language', $TRP_LANGUAGE, time() + ( 30 * DAY_IN_SECONDS ), COOKIEPATH, COOKIE_DOMAIN );
    }
}

I think I understood where the problem is.
If I am on a page like: https://mysite.com/it/page, $TRP_LANGUAGE is it_IT.
But if I go to the home page WITHOUT THE SLUG (https://mysite.com) $TRP_LANGUAGE revert to en_US. And the same happens with custom pages.
This means that by default TranslatePress does not remember user last visited language. The sell an add on to do that (didn't knew).