Adding/Activating reCaptcha on Paywall Signup Button

I need to know how to apply/activate reCaptcha on Pricing Plan and Paywall Sign-up blocks.

Background: 

We provide online training and use paywall signups to control registration and access. In this case the price is free.

The participant creates a password and provides their name and email. 

When they do this using the paywall block, they complete the following tasks in the back end: 

• Create an Account on the website
• Sign up as a Member of the specified Pricing Plan 
• Signs up for the Mailing list associated with the specified Pricing Plan

Unlike a FORM block or NEWSLETTER block, the paywall block does not have an option to activate reCaptcha. This results in the participant getting multiple emails to confirm the above actions. They get an account activation confirmation and an email verification email. 

I want this to stop and the best way seems to be to add reCaptcha on that paywall signup but I can't see how. 

Please help! 🙂

Thanks

I have the same quandary. Subscribers get 3 emails when they join my Free member area and it is...a lot.