Hi xxaimsxx,
Both for free and premium version the response of the logged in user is saved in the database as proof.
Weather they log in a different machine, clear cookie, it does not matter, as long as they use the same user, because the response is saved on the user object in WP.
The plugin provides a feature for WooCommerce when visiting a product as a non logged-in visitor. Only in that case there is a cookie user for anonymous visitors.
When a user with credentials is logged in the response is always saved in the Database of WordPress.
The premium version provides better logging mechanism and export as CSV. In the free one you can check each users edit page where a check mark will show if they have accepted.
I hope this answer your question, let me know if you have more.
Thanks,
Lehel