You obviously have no idea how the DNC works.  Once you register a phone number, that's it, no renewal is needed.

http://www.consumer.ftc.gov/articles/0108-national-do-not-call-registry

"When You Might Need to Register Again
How long does my phone number stay registered?

Telephone numbers on the Registry don’t expire. We only remove your number when it’s disconnected and reassigned, unless you ask us to remove it."