How to verify user purchase for a non-consumable product on app launch

Question

I just completed setting up inapp billing using google play billing with aidl. On successful purchase the premium feature is activated through a boolean. But after the app is closed and relaunched, premium feature disappears. ie the boolean reverts to false. I would like to know how to ensure the boolean stays as true after app launch as long as premium has been purchased.

On MainActivity

    public class MainActivity extends AppCompatActivity {

public static boolean proFeature = false;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

}

On InAppBilling Activity

    public class InAppBilling extends Activity implements IabBroadcastReceiver.IabBroadcastListener {
private static final String TAG = ".InAppBilling";

IabHelper mHelper;
boolean premiumFeature = false;
static final String SKU_PREMIUM = "android.test.purchased";
static final int RC_REQUEST = 10001;
IabBroadcastReceiver mBroadcastReceiver;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.test_lay);

}

    IabHelper.QueryInventoryFinishedListener mGotInventoryListener = new IabHelper.QueryInventoryFinishedListener() {
    @Override
    public void onQueryInventoryFinished(IabResult result, Inventory inv) {
        Log.d(TAG, "Query inventory finished.");

        if (mHelper == null) return;

        if (result.isFailure()) {
            complain("Failed to query inventory: " + result);
            return;
        }

        Log.d(TAG, "Query inventory was successful.");

        Purchase premiumPurchase = inv.getPurchase(SKU_PREMIUM);
        premiumFeature = (premiumPurchase != null && verifyDeveloperPayload(premiumPurchase));
        Log.d(TAG, "User is " + (premiumFeature ? "PREMIUM" : "NOT PREMIUM"));

        updateUi();
        setWaitScreen(false);
        Log.d(TAG, "Initial inventory query finished; enabling main UI.");
    }
};

    IabHelper.OnIabPurchaseFinishedListener mPurchaseFinishedListener = new IabHelper.OnIabPurchaseFinishedListener() {
    @Override
    public void onIabPurchaseFinished(IabResult result, Purchase purchase) {
        Log.d(TAG, "Purchase finished: " + result + ", purchase: " + purchase);

        if (mHelper == null) return;

        if (result.isFailure()) {
            complain("Error purchasing: " + result);
            setWaitScreen(false);
            return;
        }
        if (!verifyDeveloperPayload(purchase)) {
            complain("Error purchasing. Authenticity verification failed.");
            setWaitScreen(false);
            return;
        }

        Log.d(TAG, "Purchase successful.");

        if (purchase.getSku().equals(SKU_PREMIUM)) {
            // bought the premium upgrade!
            Log.d(TAG, "Purchase is premium upgrade. Congratulating user.");
            alert("Thank you for upgrading to premium!");
            premiumFeature = true;
            updateUi();
            setWaitScreen(false);
        }

    }
};

    public void updateUi(){
    button.setVisibility(premiumFeature ? View.GONE : View.VISIBLE);
    if (premiumFeature){
        MainActivity.proFeature = true;
    }else{
    MainActivity.proFeature = false;
    }
}

Answer 1

You can save it to sharedpreferences or on your server and query the status in beginning(splash screen).

or you can do a inventory query in splash screen to check the status in the splash screen.

Answer 2

In your purchase finish listener, modify below code to store value into shared preferance.

       if (purchase.getSku().equals(SKU_PREMIUM)) {
            // bought the premium upgrade!
            Log.d(TAG, "Purchase is premium upgrade. Congratulating user.");
            alert("Thank you for upgrading to premium!");
            premiumFeature = true;

            SharedPreferences sharedPref = context.getSharedPreferences(
                  "my_sp", Context.MODE_PRIVATE);
            sharedPref.edit().putBoolean("isPremium, premiumFeature).commit();

            updateUi();
            setWaitScreen(false);
        }

And on app relaunch get this value from shared preference again.

SharedPreferences sharedPref = context.getSharedPreferences(
                      "my_sp", Context.MODE_PRIVATE);
premiumFeature = sharedPref.getBoolean("isPremium, false);