You can give a client a free class in more than one way. Which ones you can use depends on your Zenamu plan.
With a 100% discount code (Expert and Ultimate)
On the Expert and Ultimate plans, during the trial and on the older Lite and Professional plans, you can use Discount codes. Create a 100% discount code for classes and share it with your clients. When they book with it, the class is free of charge.
Each discount code can be used only once per client.
Discount codes aren't available on the free Getting Started plan and the Standard plan. On these plans, use one of the options below.
Without a discount code (also on Standard)
You add the client yourself: open the class, click Add participant, choose the client and, in the list of prices, choose Custom class price. Enter 0. The booking is free.
The client books on their own: in the client's profile, add 1 entry at a price of 0 with Add custom number of entries. The client then books the class with that entry. The class must accept the entry's pass category. Entry passes aren't available on the free Getting Started plan.
For details, see How to Change the Price of a Class for a Single Client.