When your VIP subscription expires, it is automatically renewed by default for the same period of time. For example, if you have purchased 6 months of VIP membership, your membership period will be renewed by 6 months every 6 months.
To ensure that you can enjoy your VIP subscription without interruption, make sure that the payment method stored on your iTunes or Google Play account is still valid.
If you have renewed your subscription but you cannot see it in game, you will have to use ther "restore my purchase option" located here:
Other articles about the Virtual Regatta VIP Subscription: