For how long will my job post stay live?
Your post would be live for 60 days, however, you may change that.
Can I decrease the number of days that my job post is active?
Yes, you can specify the number of days after which you wish for the job post to be deactivated automatically.
You can do this after activating the post. Check this article Post Your Job to see step-by-step directions on how to post a job from the beginning.
After the post is active, edit the post and go to the next page of the post, then click on Advanced > specify the Job Closing Date (Days).