Once you are really successful, you'll know it, because spammers will try to find a way to flood your forms with unwanted subscriptions. You can build a process to filter out the unwanted traffic, but there is also a way to stop them submitting the spam entries.

You can request the installation of the reCapcha plugin to do so. Once the plugin is added to your Plugin directory, you'll be able to see it here:

In order to use it, you need to register to Google's free reCapcha service under the following link:

https://www.google.com/recaptcha/

Go to the admin console and log in / register if you are prompted to do so.

Simply create a new site:

Fill out your site information. Make sure you are using reCapcha v2, and "I'm not a robot setting".

You can choose to have alerts if someone tries to flood you with form submissions, or if there is a configuration error:

Don't forget to push Submit 🙂

After submission, your site will be listed in the admin panel. You can edit your site and get your credentials by using the Gear icon:

Once the settings open, all your credentials can be viewed by clicking on the reCapcha keys link.

Go back to your Plugins in Friendly and add the credentials as follows: