Actually you can control it from WooCommerce settings that only verified owners can leave reviews (attachment)
Got to WordPress admin > WooCommerce > Settings > Products. You’ll see a tick box called ‘Reviews can only be left by "verified owners"'. If you tick this box, only logged in users who have purchased the product will be able to leave a review. Non-buyers will see a note saying “Only logged in customers who have purchased this product may leave a review”.
