The 'Logged In' Search Subscription allows you to search for members that are currently logged into the Site.
This gives you the added benefit of knowing that should you email them, book them or interact with their profile in any other way, they will be capable of reacting or responding in a timely manner.
Once subscribed you will be able to use the "Is logged in now" tick box on the main Site Search Page.
You can subscribe to this service here
Click the relevant duration period and click the 'subscribe' box.
If you want to make sure you always have this service available, tick the 'Recur' box on this page