Yes, for ease of use, Hopster automatically renews via iTunes or Google Play. You should receive an automatic confirmation from iTunes/Google every month.
You can head to this direct link (either from your iOS device or your computer) to manage your iTunes subscriptions.
You can check out more details here directly from Apple: http://support.apple.com/kb/ht4098.
To manage your auto-renewals and subscriptions:
1. Visit Google Wallet and sign in
2. Along the left side of the screen, select 'More'
3. Select 'Subscriptions'
4. Select 'Hopster' and choose your subscription plan
Please note that since the subscription is handled through Apple's/Google's subscription system, we cannot turn off auto-renewals for your account. You will have to do it via your iTunes/Google account directly.
If you have any questions, please feel free to drop us a line at firstname.lastname@example.org