Google API - What am I looking for

Hi I tried to use the DP wordtracker tool and it asked me to sign up for a Google API. I did sign up but I'm still not sure what DP is asking for. After I signed up there's a lot of API tools by google. Which one am I looking for and what's the code to setup the DPs wordtracker tool correctly?

Thanks for your help

 

you need api key to register with DP tools.

http://code.google.com/apis/ajaxsearch/signup.html