Purchasing subscription

I’m following the Magic Weather App, all working fine but I want to update customer’s record to indicate that they subscribed. According to the quick guide I need to have the following code but the sample code missing this bit of code. My question is how is working? Does Purchases.getCustomerInfo() does the actual purchase? Please advise.

1try {
2  CustomerInfo customerInfo = await Purchases.purchasePackage(package);
3  var isPro = customerInfo.entitlements.all["my_entitlement_identifier"].isActive;
4  if (isPro) {
5    // Unlock that great "pro" content
6  }
7} on PlatformException catch (e) {
8  var errorCode = PurchasesErrorHelper.getErrorCode(e);
9  if (errorCode != PurchasesErrorCode.purchaseCancelledError) {
10    showError(e);             
11  }
12}

This is the code from the sample.
 

1  void perfomMagic() async {
2    setState(() {
3      _isLoading = true;
4    });
5
6    CustomerInfo customerInfo = await Purchases.getCustomerInfo();
7
8    if (customerInfo.entitlements.all[entitlementID] != null &&
9        customerInfo.entitlements.all[entitlementID]?.isActive == true) {
10
11      setState(() {
12        _isLoading = false;
13      });
14    } else {
15      late Offerings offerings;
16      try {
17        offerings = await Purchases.getOfferings();
18      } on PlatformException catch (e) {
19        await showDialog(
20            context: context,
21            builder: (BuildContext context) => ShowDialogToDismiss(
22                title: "Error", content: e.message!, buttonText: 'OK'));
23      }
24
25      setState(() {
26        _isLoading = false;
27      });
28
29      if (offerings.current == null) {
30        // offerings are empty, show a message to your user
31      } else {
32        // current offering is available, show paywall
33        await showModalBottomSheet(
34          useRootNavigator: true,
35          isDismissible: true,
36          isScrollControlled: true,
37          backgroundColor: Colors.black87,
38          shape: const RoundedRectangleBorder(
39            borderRadius: BorderRadius.vertical(top: Radius.circular(25.0)),
40          ),
41          context: context,
42          builder: (BuildContext context) {
43            return StatefulBuilder(
44                builder: (BuildContext context, StateSetter setModalState) {
45              return Paywall(
46                offering: offerings.current!,
47              );
48            });
49          },
50        );
51      }
52    }
53  }