$re = '/(?:\G(?!^);|Seats:\s*)\K\d+/m';
$str = 'Seats: 11;12;
Name: qqqq;wwww;
Start: Прешов, АВ Košická 2725/2
End: Мукачево, АЗ Лавковская, 1б
Date: 2019-06-22
Time: 09:40 PM';
preg_match_all($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