- var_dump: documentation ( source)
- preg_match: documentation ( source)
<?php
$message = "<@204982556188213248> remind me about Things that make me go pop 12123 at 2016-03-01 08:00 GMT remind me then";
preg_match('~(at\s)(.*)\sremind~', $message, $matches);
var_dump($matches);