I’ve gotten email saying “Your certificate (or certificates) for the names listed below will expire in 8 days (on 06 Sep 20 00:29 +0000). Please make sure to renew your certificate before then, or visitors to your website will encounter errors. …”
I have this domain through Amazon Web Services, and am up to date with payments there. I can’t see where to pay for this, or how. (Also, I am new to this!)
@ravivakil You are indeed hosting the server on Amazon AWS, do you know whether you are using AWS LightSail or AWS EC2? And how (or who) did you get the site? (i.e. installed it by running a script? Hired a freelancer? friend?)
I honestly think he might just forget to enable auto-renewal or your site changed something that the auto-renewal is failed. However if you don't know or don't have SSH access, it's better to contact your friend
P.S. A (sort of) important suggestion: Your site experience might be better if you also point your www hostname to this server and also setup TLS certificate (in fact, it can be a single certificate including both hostnames!).