<?php
$string = 'http://n...content-available-to-author-only...e.com/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiYWRtaW4iOnRydWV9.TJVA95OrM7E2cBab30RMHrHDcEfxjoYZgeFONFh7HgQ/additional/segments';
$regex = '~^http://.+?/(?P<token>[^/\n\r]+)~';
preg_match($regex, $string, $match);
echo $match["token"];
