Yes, PCI-DSS rules state one is not allowed to store the CVV, therefore for subscription services or for things like one click ordering or app stores the CVV is

Yes, PCI-DSS rules state one is not allowed to store the CVV, therefore for subscription services or for things like one click ordering or app stores the CVV is not used for the transaction, though they may verify it on initial card entry a lot of companies don't as it doesn't actually help. Taking the CVV gives a lower fee to mastercard/visa if that particular transaction is reversed, this is how stores are incentivised to take it but it will only apply to initial transaction where card details are saved.