If I understand correctly, I think you don't need to make your own API calls to get the "order" details.
If you mean to
query the purchases for Google in-app billing,
Wait For (billing.ConnectIfNeeded) Billing_Connected (Result As BillingResult)
If Result.IsSuccess Then
Wait For (billing.QueryPurchases("inapp")) Billing_PurchasesQueryCompleted (Result As BillingResult, Purchases As List)
Log("Query completed: " & Result.IsSuccess)