$re = '/=> ([A-Z0-9]{6})\)/m';
$str = 'Array([0] => Array([0] => CLASSI[1] => LEATHE[2] => 0MEFCQ))
VANS CLASSIC SLIP-ON CROC LEATHER 0MEFCQ 36-40
([0] => Array([0] => TRAMPK[1] => XH8GKA))
NOWE TRAMPKI VANS SK8-HI SLIM ZIP XH8GKA 36-40
([0] => Array([0] => DAMSKI[1] => TRAMPK[2] => AUTHEN[3] => EE3W00))
DAMSKIE TRAMPKI VANS AUTHENTIC EE3W00 35-41';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php