The LetsEncrypt certificates expire every 90 days. You will get a reminder email from the LetsEncrypt CA a couple of weeks before expiry.
Here is the email that I received
From: <email@example.com> Subject: Let's Encrypt certificate expiration notice Message-Id: <20160322T090444.firstname.lastname@example.org> To: <email@example.com>Hello, Your certificate (or certificates) for the names listed below will expire in 19 days (on 11 Apr 16 06:10 +0000). Please make sure to renew your certificate before then, or visitors to your website will encounter errors. sandbox.pascoe.biz ses.rosacea-support.org For any questions or support, please visit https://community.letsencrypt.org/. Unfortunately, we can't provide support by email. If you are receiving this email in error, unsubscribe at LINK (HTTP link, we know. We're working on it!) Regards, The Let's Encrypt Team
To renew your LetsEncrypt certificate, go to the place where you installed the LetsEncrypt client ;
command: ./letsencrypt-auto renew
bitnami@ses:~/le/letsencrypt$ ./letsencrypt-auto renew Updating letsencrypt and virtual environment dependencies...... Requesting root privileges to run with virtualenv: sudo /home/bitnami/.local/share/letsencrypt/bin/letsencrypt renew Processing /etc/letsencrypt/renewal/ses.rosacea-support.org.conf new certificate deployed without reload, fullchain is /etc/letsencrypt/live/ses.rosacea-support.org/fullchain.pemCongratulations, all renewals succeeded. The following certs have been renewed: /etc/letsencrypt/live/ses.rosacea-support.org/fullchain.pem (success)
Then restart your web server and you should see the renewed certificate being served to your site visitors.