You may resolve this, if you will create cron jobs, This Jobs will run every day, and remove or hide all instances with date create/change more 30 days ago.
Or you may earn money with help CCK ordasoft.com/cck-content-construction-kit-for-joomla.html,
from item additional show.
In CCK, We have Featured fields
Every Item - you may mark as "featured" - these items for you most important to show for users
We in every item have "Featured fields": "Featured click" and "Featured show"
Items with not zero "Featured" fields you may show in "featured layout"
Every click by this item or show this item - subtract these fields by 1.
When both "featured" fields will equal zero - Items will leave from the "Featured module"
These fields in Content Contraction kit can set only admin