If a client has purchased courses and wants to use a course session to pay for a treatment, you can do so from the 'Account' screen where you would usually capture payment from the client.
If a client wants to redeem a course session, they can only do so if they have remaining sessions available and if they have a course that matches the treatment they came for. E.g. If a client comes for an underarm laser treatment, and has not purchased a course that has that service allocated to it, they cannot use it to pay for their session.
From the account screen (where you would usually capture a payment), if the client has courses allocated to their profile, the 'Add Payment' button will give you the option to either capture a regular payment, or redeem a course session:
From here, you can choose which course you want to charge (if the client has multiple courses with you), and which service you are paying for with a course session:
Once you have chosen the course and selected the treatment the client is paying for, click on 'Redeem Course Session':
This will apply a discount to the service (if applicable) and deduct a course session from the customer's available course sessions. It also logs a payment on the account so that your cash up balances and you can check how much has been redeemed over a date range using your payments report.