With YITH WooCommerce One-Click Checkout users can skip the checkout process once the billing info has been added. After activating the plugin please checkout the settings here to manage when the button will be displayed.
In the example above, the customer sees the ‘One–Click‘ button because it is his second order. The One-Click button has been set to be displayed after the first order.
Please make sure that billing info has been entered, either because it is the second purchase, or in the my account page, in order to see the ‘One-Click’ button.