Select Business Settings (mobile: Profile → Settings) → Payments & Checkout → No-Show Protection. From there, you can enable No-show Protection and adjust the settings for this feature.

You can choose from two options:

1. Deposits: At the time of booking, the client pays either the partial or full price of the service upfront. The deposit amount is deducted from the total at checkout. 
2. Cancellation Fees: At the time of booking, the client will be asked to provide their credit card information. If they cancel last-minute or don’t show up, you will be able to charge their card for the cancellation fee.

You may choose to apply No-Show Protection only to specific services. 

Note that you need to enable Mobile Payments in order to use No-Show Protection.