To use Google reCaptcha on your website, you will need to have a Google reCaptcha API Key and Site Secret. You must have a Google account to get a Google reCaptcha API key/site secret. If you do not have a Google account you can get one here:
Get Your Google reCaptcha API Key/Site Secret - Use the following link to create a key/site secret https://www.google.com/recaptcha/admin#list
Download instructions with screen shots.