This article explains how to check the expiration date of your SSL certificate on Plesk.
1. Log in to your Plesk Web Admin control panel
2. Look for SSL/TLS Certificate and click on it
3. After clicking on SSL/TLS Certificate, you will be directed to the SSL/TLS Certificate page for domain.com.
Displayed below is (Valid To: October 10, 2021), indicating the expiration date of your Certificate.
Alternatively, you can verify using an online platform: https://www.sslshopper.com/