This post is a short instruction to show how to get the API key for the 2captcha service.
If you have no account on 2captcha.com, go to the site and press Sign Up:

Enter your email and a password:

You will see the confirmation popup:

Open the inbox and check the letter from 2captcha. If your Inbox has no new emails, check the Spam folder:

Open the email, find the confirmation link and go by it:

You will see multiple roles. Select the appropriate role for you:

After redirection you can find your API key:
