iRocket technical support team resolved my confusion.
iRocket has been one of my favorite software tools in developing high quality music in my personal DAW. However, perhaps due to some mis-operation, by my side, there was a situation that two duplicated subscriptions existing, and the worse is I have been unaware of that. One day I received a notice of automatic renewal of the subscription, but that was different from the one I remember, so I was confused and tried to cancel it but unsuccessful. Maybe I was unsuccessful in locating the appropriate duplicated one. Then, iRocket Technical Support staff, Ms. Anna kindly provided the explanation that I have kept two subscriptions and I failed cancellation of the appropriate one of them (the one with earlier expiration). Not only the explanation, but Ms. Anna, confirmed my true intention to avoid unnecessary duplicated subscription, she kindly offered the support from their side to merge two into one and applied the last due date. I understand that this support is largely customer satisfaction oriented, the extent to which has never been experienced before.