$re = '/(?:^<@([A-Z0-9]+)>)*.+[\s]([0-9]+)/m';
$str = '<@U0BUPU9QQ> 49
50
<@U0BUPU9QQ>
<@U0BUPU9QQ> noget 49 noget andet tekst 5 40
<@U0BUPU9QQ> noget andet tekst 5 40
<@U0BUPU9QQ|mn> has joined the channel';
preg_match_all($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