Why would I be getting these errors in my error logs..

18-Jun-2019 17:11:43 America/New_York] PHP Fatal error: Class 'ReCaptcha\ReCaptcha' not found in /usr/home/***/public_html/******/includes/classes/observers/class.google_recaptcha.php on line 37

[18-Jun-2019 17:11:43 America/New_York] Request URI: /index.php?main_page=create_account, IP address: ********
--> PHP Fatal error: Class 'ReCaptcha\ReCaptcha' not found in /usr/home/*****/public_html/********/includes/classes/observers/class.google_recaptcha.php on line 37.

Thanks!