A promissory note is a legal document between the borrower and lender for full mortgage repayment. Learn how promissory notes work and what is included.The promissory note details the loan amount, interest rate, payment schedule and term length. To sell a promissory note, evaluate its value, find a buyer, negotiate terms, and complete the legal documentation with an online notarized affidavit. A Texas Deed of Trust creates a lien on property to secure a Promissory Note. These are two documents needed for real estate loans and seller financing. When a promissory note is lost, the lender must write an affidavit for the lost note to prevent any investment loss.