This web-service runs on Google's app-engine system which should be free to use as it fits within the free usage levels.
It receives data sent over the cellular network from The Parakeet unit and then returns this information to xDrip or xDrip+ running on Android.
Step by Step instructions for installing it are availble in the Parakeet & Google App Engine Guide PDF
Click the image above to view the Google Cloud Shell installation screen-cast. See the guide PDF for more details.