Yes, it auto-renews each month if you've selected a monthly subscription, or each year if you'd selected an annual subscription. You can cancel your subscription at any time by tapping ‘Manage Snoop Plus Subscription’ in settings. After cancelling you’ll have access to Snoop Plus until the end of your current billing period.
You can check how much you are paying by visiting the app store for your device (Google Play, App Store or Huawei Gallery).