Recording Storage gives you the option to view and manage all of your Account's Call Recordings and their storage. Head to My Account > Billing & Logs > Recording Storage to view storage, statistics, and delete any past recordings you no longer need.

Recordings associated with your smrtPhone Account are billed monthly for storage, and you can see the total recorded minutes along with the correlated storage cost. The flat rate for recordings is $0.0010 / recorded minute. To reduce the amount you are charged for recording storage, you can delete any past recordings that you no longer need. 

If you want to keep any particular recording, access the phone call logs and then mark that particular one as Prevent Delete.

This way, when you delete an entire month of calls, those marked calls will be kept in the Recording Storage.