text_test.php

<?php

$reg_exp = '#<a [^>]*href=\\?[\'"](?P<url>http:\/\/[0-9a-z]+\.[0-9a-z]{5,10}\.(pay|hop)\.clickbank\.net)\\?[\'"][^>]*>#is';

$text = '
ololololol trolololololol
<a href=\"http://123.ololo.pay.clickbank.net\">ololol trololo</a>
<a href=\"http://affiliate.ol00lo.hop.clickbank.net\">ololo trololo</a>
';
$matches = array();
echo 'Matches: ', preg_match_all($reg_exp, $text, $matches) , PHP_EOL;