To get your free Google reCAPTCHA V2 API keys, the only need a google account (a Gmail account). So, to be sure that you have Gmail account before going to the Google reCAPTCHA website. if you do not have Gmail account then first you create a new account, you can sign up for a free Google account here

Below are the few simple steps you have to follow to get API Keys:-

Step 1.

Once you have your Google account ready, head to the Google reCAPTCHA website.
There is Get Recaptcha button in the upper-right corner:

Before login in your Gmail account, if you click in to get reCAPTCHA, you may be asked to enter your user id and password and then again to click get reCAPTCHA. Otherwise, you cannot be logged in into your Google reCAPTCHA account.
Step 2.

In the Register a new site section, Enter the label in Label Box for which you want keys. Then click on reCAPTCHA V2 button and enter URL of your site without with http://. in the Domains box.

After you Accept the reCAPTCHA Terms of Service , you can click Register button to get new API key pair.