As a result of an expired provisioning profile and format change in the developer certificate, customers who downloaded 1Password for Mac directly from our site will need to manually update to the latest version. Those using 1Password from the Mac App Store are not affected.
AgileBits’ blog post goes into the details of what happened. Like with the recent Instapaper outage, the honesty makes me feel better about the issue.
Update: Other Mac developers are dealing with this as well.