Current bot cookies are available through getHttpClient and cookie/cookies methods. All cookies:
$cookies = $bot->getHttpClient()->cookies();
Cookie value by name:
$someCookieValue = $bot->getHttpClient()->cookie('cookieName');
By default cookie files are stored in your system temp directory. You can set custom path to store cookies. Notice! This path must have write permissions:
$bot->getHttpClient()->setCookiesPath($yourCustomPathForCookies);
$currentPath = $bot->getHttpClient()->getCookiesPath();
Remove your cookies:
$bot->getHttpClient()->removeCookies();