I'm new to Apple Developer and am having difficulty with terminology and location of certificates.
The subject of this post is the email I received from Apple. It says my iOS Distribution Certificate is set to expire. The problem I am having is that all of my certificates are set to expire either in 2016 or 2017, far outside the 30 day window the email is saying. Am I looking in the wrong place?
I also looked Provisioning Profiles > Distribution to no avail.
Regarding your distribution certificate, once it expires, it simply disappears from the ‘Certificates, Identifier & Profiles’ section of Member Center. If you want to renew it before it expires, revoke the current certificate and you will get a button to request a new one.
Regarding the provisioning profile, don't worry about it before expiration, just keep using it. It's easy enough to just renew it once it expires.
Look in Certificates > Production for a certificate of type "iOS Distribution". Your Distribution Profiles are signed using your Distribution Certificate. To create a new certificate, click the + (above and to right of list) and choose "In-House and Ad Hoc" under Production. Here's the iOS App Distribution Guide.
EDIT: See especially the section "Maintaining Your Signing Identities and Certificates".
EDIT: Also see the section "Distributing Apple Developer Enterprise Program Apps".