bottles and accessories to sterilise.

There's are so many bottles and accessories to sterilise. N my steriliser has limited storage. How do I keep those sterile bottles n accessories? Can I keep them In air tight container n leave it at room temperature? Or must I keep it in my steriliser? How do I know the bottles or accessories need to sterilise again, I mean how Long do they stay sterile out of the steriliser? And Isit necessary to sterilise every 2 hours despite not using it?