Free Standard Listings
Free business and event listings never expire and will be active until you decide to remove it.
Enhanced Listings
If you have purchased the "Enhanced Listing" package your business listing will be active as featured for 12 months and your event listing for 6 months.
After such period of time the listing expires and it will no longer be visible online.
In order for the listing to be visible online again, you need to go to your dashboard and republish the listing as a free "Standard Listing" Package or "Enhanced Listing" Package.