Replaces the built-in CAPTCHA on member registration and comment forms with KeyCAPTCHA.
Go to https://www.keycaptcha.com/captcha-for-free/, select your CAPTCHA type, and fill in the details. Replace USER_ID_HERE and PRIVATE_KEY_HERE in keycaptchalib/keycaptcha.php with the site-generated strings and place this directory under expressionengine/third-party.