Job postings on our site have a life span set by the employer. They expire unless renewed or reposted (by the employer). At any point during their run, jobs can be manually deleted by the companies. In either case, they will no longer appear on our site, and you can no longer submit your resume to the job. Unfortunately, this is something that is specified on the employers' part, and not on the part of Avjobs.
Job postings routinely expire in 30 days to keep things fresh.