To get started, you will need to create the plans as outlined in Stripe or Braintree's documentation. If you don't have a Stripe or Braintree account, then sign up for an account with either of them and proceed to create your plans.
Once you have created your plans in your Stripe or Braintree account, connect your account under Account Settings → Account Services by selecting "Connect Braintree" or "Connect Stripe".
In the form editor, ensure that the desired payment account is selected under Configure → Payments.
Create a question, and set the question type to “Subscriptions”.
Under the configure section (cog icon) for the subscriptions question, you will see a list of available plans. Click on the plan to move it over to the "Selected Plans" section for this question.
Optionally, toggle on “Can choose more than one subscription” if you would like the submitter to be able to add multiple subscriptions at once. You can also toggle on the option "Discountable" if you would like to discount a Stripe subscription.
Ensure you scroll through and configure the available settings for Payments and Subscriptions and make your selections.
Test your form.
You may wish to allow for a recurring payment that expires after a set period of time. To enable this, when creating a plan in Braintree, you can specify the billing cycle length and the number of billing cycles.
For example, suppose you wish to charge someone monthly for a period of four (4) months. You would set up a plan in Braintree with the billing cycle length set to one (1) month and the number of billing cycles set to four (4).