What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
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I would like to recommend you to delete mentioned subscription form your payment form, if it is still exists.
Then, you may provide your customers with the following subscription cancellation instruction from http://support.google.com/checkout/bin/answer.py?hl=en&answer=1090911
Cancel recurring subscription payments
You can stop your subscription service at any time:
1. Go to https://wallet.google.com/manage and sign in to your Google Wallet account.
2. On the Transactions page, click the View Order link for the subscription you'd like to cancel.
3. Click the Cancel subscription button.
You may also try to contact Google Checkout support for further assistance.
Please feel free to contact us if you have any other questions.