Using a captcha can help prevent spam. One of the best solutions out there is the Google ReCaptcha – it’s free and not too intrusive during form submission.
The first thing you have to do is getting a Site Key and Site Secrete, You can get the Site Key and Secret Key on Google reCaptcha Dashboard. Click here
1) Register Your Domain’s Name:
After filling out this form you will get the Site and Secret Keys.
Obtaining Site Key & Secret Key:
Copy&Paste these values because you will have to use it on the reCaptcha.
Activating reCaptcha on the Plugin:
Login to your WordPress Dashboard, click on WP Users Pro Settings then on reCaptcha tab.
Click on the pages you would like to display the reCaptcha.