Fee structures are added to the top level client record, and then within each client account you determine which charging structures apply.
This means that you can share structures across client accounts rather than have to duplicate the same settings multiple times.
There are various options on determining commission rates, taking into consideration the length of time or age of the account.
Flat charges can also be used and automatically generated based on actions e.g., a trace action can generate a fee.
All of these financial charging structures are stored on the ledger and available for reporting/export to drive your invoicing systems and track fees throughout the period.