We've always expired backfilled jobs when the role disappeared from the careers page.
Automatic job expiry now covers imported jobs as well — CSV, XML, recurring feeds, and jobs you add yourself. If the apply link is dead, the listing expires. It runs on every board. There is nothing to turn on.
Paid job submissions are left alone. Those are yours to expire.
See Expired jobs for what candidates and search engines see after a job expires.