$re = '/^(?=(?:[a-z0-9]*[a-z]))(?=(?:[a-z0-9]*[0-9]){3})[a-z0-9]{10,}$/mi';
$str = 'X6JV2YUW8T
JN1H86LEKA
111JEJE134
A111111111
ABCDEFGHIJ
0123456789
X6JV2YUW8T => True
JN1H86LEKA => True
111JEJE134 => True
A111111111 => True
ABCDEFGHIJ => False
0123456789 => False';
preg_match_all($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