If you purchased an annual subscription, that means you can use the program as long as your subscription is active. To note, subscriptions are renewed automatically until cancelled by users. If you do not wish to subscribe and use the program, then you can manage your subscription here: nch.com.au/support/manage-subscriptions.html
If you subscribed by mistake and want to request a refund, you can do that by contacting the support team with this link: https://www.nch.com.au/support/index.html