You can configure a software update to expire as soon as it is superseded by a more recent software update or to expire after ...

You can configure a software update to expire as soon as it is superseded by a more recent software update or to expire after a specified period of time when it is superseded by a more recent software update.

Supersedence settings do not apply to System Center Endpoint Protection definition updates or to software updates that are superseded by Service Packs. These software updates never expire when they are superseded.

Changing this setting will force a full software update point synchronization.