Converting paid app into subscription

Hello, 

First of all I want to thank you for this great framework. My app has been downloaded more that 20K, now I am about to release the the new update, and also, I have read this article.

Just have a question, my new update version for both app version and build is 11.0, so I need to detect if the originalApplicationVersion  of previous users (who bought the app) is less than 11 the app should unlock the premium version. So I am doing it like this, and I was wondering am I doing it right?

First setup configurations:

init() {
		Purchases.logLevel = .debug
		Purchases.configure(
			with: Configuration.Builder(withAPIKey: "appl_mj*****")
				.with(usesStoreKit2IfAvailable: true)
				.build()
		)
		Purchases.shared.delegate = PurchasesDelegateHandler.shared
	}

and then detecting it using delegate:

func purchases(_ purchases: Purchases, receivedUpdated customerInfo: CustomerInfo) {
        SubscriptionManager.shared.customerInfo = customerInfo

		if let version = Double(customerInfo.originalApplicationVersion!) {
			if version < 11.0 {
				print("premium unlocked")
			}
		}
    }

as the article mentioned the sandbox always gives me version 1.0. So I was wondering is this the right approach to release the app on the app store?

Thanks!