WooCommerce Auto Restore Stock will automatically restore your WooCommerce inventory/stock for orders that was placed and refunded or cancelled.
The inventory/stock restore is triggered when the order goes from on-hold, processing, completed to either cancelled or refunded status.
When WooCommerce Auto Restore Stock restores the inventory/stock it will also add order notes to the order in question to show the adjusted values and to indicate that inventory/stock was restored.