How to include the Google Play Services RSA public key in my Android app binary

Google Play given me this public key.

How to, and where to use this public key? How can i include it to my binary?

I’m also wondering about this - the wording implies it’s mandatory if your app will be paid, but I haven’t been able to find instructions on how to include this with the private key as detailed here:

http://ionicframework.com/docs/guide/publishing.html