You can cancel your LumaBooth subscription at anytime.
App Store Subscription: Subscriptions are handled by Apple through the App Store. To cancel subscription, follow these instructions. If you need to request a refund, you can do so at Apple's support site.
LumaBooth Direct Subscription: You can cancel through fotoShare Cloud (Subscriptions > LumaBooth). Click the Billing tab, then click Cancel Subscription Renewal.
If you are not sure what type of subscription you have, you can see your subscription status at fotoShare Cloud > Subscriptions > LumaBooth. Login with your email you have set to login to LumaBooth.