YITH WooCommerce Subscription is a plugin designed to enable recurring payments for the services offered in your shop.
When used in combination with YITH Donations for WooCommerce, it allows turning the product created by the plugin (named YITH Donations for WooCommerce) into a subscription-based product and receive recurring donations from your customers.
After installing and activating both plugins, go to WooCommerce > Products and search for YITH Donations for WooCommerce. In the product edit page, enable the checkbox Subscription.
Now you will be able to set the subscription details like for any other subscription-based product.
For further details about YITH WooCommerce Subscription settings, please refer to the official documentation.