I see examples of recurring subscriptions with variable amounts but where is the number of payments?

I see several examples of recurring subscriptions with variable amounts.  The screen shots and examples show a Number of Payments option in the wizard.  Yet, when I go in to set up a form, I see no such option.  What am I missing?  

Hi,

Please see my colleague Mike's reply here. Unfortunately, as he has implied, this isn't possible with the payment integration you're currently using: Stripe.

Thanks