Receipt verification

I have one non-consumable IAP in iOS app (premium update)

1- Should I call this verify method every time the user opens the app

let appleValidator = AppleReceiptValidator(service: .production, sharedSecret: "xxxxxxxxxxxx")
SwiftyStoreKit.verifyReceipt(using: appleValidator, forceRefresh: true) { result in
switch result {
case .success(let receipt):
print("success: \(receipt)")
case .error(let error):
print("Verify receipt failed: \(error)")
}
}

To make sure app is truly paid and IAP not hacked ?

2- Also inside the success block i should open the app premium features , while inside failure i should lock them ?