In app billing error how to fix

in app billing refund issue
i try some components
But found this issue ( Give me solution

Please show what you tried.

As the message is trying to tell you… you have to Acknowledge your purchase after buying…

Are you using Kodulars billing component?
See the documentation of my billing extension here App Inventor Extensions: Billing | Pura Vida Apps

Acknowledge purchases : your app must consume or acknowledge all purchases. This is a new feature Google added into the Billing library to prevent fraud. If you don’t consume or acknowledge a purchase within three days, Google automatically revokes the purchase and refunds the user.
If your app has a validating server component, you should only acknowledge a purchase after successfully validating it.

Verifying purchases is not required, but is considered a best practice when selling in-app products. For more about how to fight fraudulent purchases, check out chapter Verify purchases before granting entitlements in the Fight fraud and abuse page and chapter Processing Purchases in the Integrate the Google Play Billing Library into your app page.
After verifying the purchase, your app then needs to acknowledge the purchase.

How my billing extension can help:

If you decide to not verify the purchase, you can use the AutoAcknowledge feature of the extension to automatically acknowledge after purchasing. If you choose to verify the purchase, use the PurchaseUpdated event to get the purchase token and follow chapter Verify purchases before granting entitlements in the Fight fraud and abuse page. After successful verification then use method Acknowledge together with the purchase token to acknowledge the purchase.


how to buy this in app billing extension
and after purchase how to use it …

You can find the answers to your questions here
Protip: read the complete page until you find also the large green box on the bottom there