In the free IP address tracker you can click on a button called credentials and settings. There you can add multiple SNMP community strings, I don't default most of my stuff to public for a reason. It would be nice to add my customized strings to the list for the poller like I can with your free product. I have opened a ticket with support and they suggested if I wanted make a feature request. Case #585538. If anyone has any questions on my idea let me know.
Thanks,
Ray