i've got The request returned the following error

i've just tried http://www.digitalpoint.com/tools/suggestion/ but it results error.

The request returned the following error:
Exception from service object: Invalid authorization key:

i assume the error is i type error API code.what is google api? is it same with google MAPS API? i have insert google maps api to signup. what is correct api to signup to using this service? thank you

regards
agus

 

i've done until http://code.google.com/apis/apps/overview.html where can i get the code?