In the "My Tickets" area of the Passenger Portal, your Flexi ticket will be listed and it will display the current trip balance left on the ticket.
Each time you scan your ticket this is recorded as a trip and this will deduct the value of one trip from your trip balance.
For more detail about how your balance has been calculated, hit the "Details" button on the ticket, and then "View trips". The "View trips" area will display all trips used with this flexi ticket.
Please note the balance may have a delay in being updated depending on when your transport operator is able to sync their recent ticket scan data.