If you have a subscription of Cost of goods for WooCommerce you are able to use the cost of goods values you already have in the Cost & Reports. Be aware that you do not need this extension to use Cost & Reports, Cost & Reports creates this field (cost of goods) for you by default on installation. Start by go to WooCommerce > settings > Cost & Reports > Integration. Set the following options:
When you have done this and saved you can go back to Cost & Reports. Now you will see all your cost of goods values is on the products and can use them for the calculations of your products and variations.
Cost of goods field created in Cost & Reports is: _cost_of_goods