subscription should use this launchSubscriptionPurchaseFlow

** Activity (main) Pause, UserClosed = false **
sending message to waiting queue (OnActivityResult)
running waiting messages (1)
Arrived: 1, 1
Ending async operation: launchPurchaseFlow
Successful resultcode from purchase activity.
Purchase data: null
Data signature: null
Extras: Bundle[{RESPONSE_CODE=0}]
Expected item type: inapp
BUG: either purchaseData or dataSignature is null.
Extras: Bundle[{RESPONSE_CODE=0}]
IAB returned null purchaseData or dataSignature (response: -1008:Unknown error)
** Activity (main) Resume **

I checked stackoverflow found a topic http://stackoverflow.com/questions/...ns-error-code-1008-null-puchasedata-or-datasi

according tho them the problem is :
"If you call mHelper.launchPurchaseFlow(...) with an SKU that is registered as a subscription on Google Developer Console it will result in the error: IAB returned null purchaseData or dataSignature (response -1008:Unknown error).


If you have a SKU that is registered as an 

subscription you have to use the 

method:mHelper.launchSubscriptionPurchase

Flow(...) instead."

NOT launchPurchaseFlow(...)

//                mHelper.launchPurchaseFlow(InAppTestActivity.this, strItemId,
//                        1001, mPurchaseFinishedListener, payload);
// 2017/09/24
                mHelper.launchSubscriptionPurchaseFlow(InAppTestActivity.this, strItemId,
                        1001, mPurchaseFinishedListener, payload);

How can i fix this bacause it is impossibe to activate a feature upon purchase. Alotugh the charge is made to customers credit card , event not firing until relaunch?