Connect the notifications access points between Google Play console & OKAST for in-app purchases and subscriptions on Android : Support OKAST

Before creating in-app purchases or subscriptions on your Android mobile app, you will need the URL field Google Play S2S Notifications Endpoint: ask for it to your account manager at OKAST or send your demand by email at devapp@flamefy.com. You will need it during the described process below.

Creation of a new Pub/Sub topic

Connect you at the the console of the Google Cloud platform
Create a new topic Pub/Sub
Google Cloud Platform > PubSub > Topics > + Create topic

Name the new topic Playstore-S2S-notifications on the topic ID
Leave the encryption on the key managed by Google

Creation of a subscription on the Pub/Sub topic

Access the topic you just created
Click to the bottom of the page on + Create a subscription > Create a subscription (Create a simple subscription)
Set the Delivery Type on Push
In the Endpoint URL field, enter the Google Play S2S Notifications Endpoint URL that was provided (cf. top of the article)
Set the Message retention duration at 7 days
Don’t set expiration date on the Expiry period area
Set the Acknowledgment deadline period at 60 seconds

Add an editor to the Pub/Sub topic

Add a new permission to the Pub/Sub topic in the Google Cloud Platform console : PubSub > Topics > [Playstore-S2S-Notifications] > ADD PRINCIPAL
Copy and paste the following value in the member field google-play-developer-notifications@system.gserviceaccount.com
Set the role on Pub/Sub Publisher

Test

Log in to Google Play Console and go to the following section: Google Play Console > [YOUR APPLICATION] > Monetize > Monetization Setup > Real-Time Developer Notifications
Enter the full name of the topic. It must have the form projects/[YOUR PROJECTS]/topics/Playstore-S2S-Notifications
Click on the Send Test Notification button
Check that the test notification has been received at the topic level in the Google Cloud Platform console: Google Cloud Platform > Topics > Googleplay-S2S Notifications
Check that the test notification has been received at the subscription level in the Google Cloud Platform console: Google Cloud Platform > Subscriptions
Click on Save changes

Everything is ok, you can now create your in-app purchases and subscriptions in the Google Play Console. Read more about the Google Play Console just here.