Q:

Places API Billing - am I charged for only including the places API js?

First of all sorry if this is the wrong place to ask this - waiting for the company's credentials to open a google support ticket.
I can't find a clear answer for this - does the Places API charge us for just including <script src="https://maps.googleapis.com/maps/api/js?key=..."></script>, even if the user does not type on the widget?
In my billing report, along with API request billings, I see these lines:

"Autocomplete without Places Details - Per Session"
"Autocomplete (included with Places Details) - Per Session"

A:

You will not be billed if you include libraries=places in 
<script src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&libraries=places&callback=initMap"
        async defer></script>

You will also not be billed for the Autocomplete Widget if it did not get any interactions from your user (e.g. Typing places). You will only be billed for 

Autocomplete without Places Details - Per Session

If you type in the autocomplete widget but did not select any suggestion. And for 

Autocomplete (included with Places Details) - Per Session

You will be billed for this if you type in autocomplete widget and select a suggestion. Note that if you this SKU is billed in your account, the Autocomplete request will be free and you will only be billed for the Place Details request.

