go get github.com/awa/go-iap/appstore
go get github.com/awa/go-iap/playstore
go get github.com/awa/go-iap/amazon
go get github.com/awa/go-iap/hms

import(
    "github.com/awa/go-iap/appstore"
)

func main() {
	client := appstore.New()
	req := appstore.IAPRequest{
		ReceiptData: "your receipt data encoded by base64",
	}
	resp := &appstore.IAPResponse{}
	ctx := context.Background()
	err := client.Verify(ctx, req, resp)
}

import(
    "github.com/awa/go-iap/playstore"
)

func main() {
	// You need to prepare a public key for your Android app's in app billing
	// at https://console.developers.google.com.
	jsonKey, err := ioutil.ReadFile("jsonKey.json")
	if err != nil {
		log.Fatal(err)
	}

	client := playstore.New(jsonKey)
	ctx := context.Background()
	resp, err := client.VerifySubscription(ctx, "package", "subscriptionID", "purchaseToken")
}

import(
    "github.com/awa/go-iap/amazon"
)

func main() {
	client := amazon.New("developerSecret")

	ctx := context.Background()
	resp, err := client.Verify(ctx, "userID", "receiptID")
}

import(
    "github.com/awa/go-iap/hms"
)

func main() {
	// If "orderSiteURL" and/or "subscriptionSiteURL" are empty,
	// they will be default to AppTouch German.
	// Please refer to https://developer.huawei.com/consumer/en/doc/HMSCore-References-V5/api-common-statement-0000001050986127-V5 for details.
	client := hms.New("clientID", "clientSecret", "orderSiteURL", "subscriptionSiteURL")
	ctx := context.Background()
	resp, err := client.VerifySubscription(ctx, "purchaseToken", "subscriptionID", 1)
}