If you've issued your LE certificate manually then renewal will not happen automatically.
LE certificates expire after 90 days, so you'll want to set up a cron job to renew it after 80 days or so, to give you some time to deal with potential problems with renewal.
Note that as of several months ago we support automatic LE provisioning for any domain or subdomain that points to your Opalstack server IP, regardless of the name servers used by the domain. If you're manually managing a certificate used for a website that you host at Opalstack, then you can probably stop doing that and use our automatic LE instead.
