Stripe: Subscription Forms
You need to add plans in Stripe if you haven't already done so.
Note the ID in each case. This is our Plan ID.
In this case, we define a plan ID when configuring the Stripe field.
We can have a checkbox field which allows users to select the relevant plan.
Our Select Plan field would look like this:
The field id is field5
So, naturally, the Stripe Plan ID would be a reference to this field: