So this annoyed the fuck out of me, hopefully someone else can pick up where I couldn't.
The Google Adwords Desktop Tool uses their API. You do not pay to use the API when you use the desktop tool. That means someone - if they have enough time or skill - should be able to figure out what key they're using or how they're keeping it from billing.
I got frustrated with it like 2-3 years ago and stopped fucking with it...but hey. Maybe someone else will have luck.
If you figure it out, drop me a PM with it for the tip. I don't advertise on Adwords, but god damn it I want to know.