How to choose the most appropriate one? Preclosing liabilities in the face of express contractual language in the asset purchase agreement to the contrary.The letter must outline your complaint, the harm you suffered, and how you want the problem resolved. This is called a 30 Day Demand Letter. Learn more about the terms of a purchase and sale agreement. Contact Attorney Peter Chase for more information. An asset purchase agreement (APA) might benefit a buyer who wants to exclude liabilities or redundant assets.