Anytime you are sent product by a brand, regardless if payment is involved, you must follow all collaboration details and post by the post date. Lack of following through with the entire collaboration could result in a suspension!
However, we understand not all products are for everyone. If the product ends up being incompatible to your brand or you experienced a bad reaction, let the brand know so they can provide a return label and cancel the collaboration.
Keep in mind, each campaign detail page indicates whether or not payment is involved.