Running CB 2.0.7, PHP 5.5.21. CBSubs GPL 4.0.0-rc.2 also. I just upgraded on a test site from CB 1.9.1.
The URL for the Mass Expiry cron job on Settings->Global is incorrect. It is listed as
http://AIRW/index.php?option=com_comprofiler&task=pluginclass&plugin=cbpaidsubscriptions&do=&key=KEY&format=raw
Note empty &do=&
When I set do=massexpire, it works.