Statement of Use
SOU - a sworn statement signed by the applicant or a person authorized to sign on behalf of the applicant attesting to use of the mark in commerce. With a statement of use, the owner must submit: (1) a filing fee of $100 per class of goods/services; and (2) one specimen showing use of the mark in commerce for each class of goods/services.
Statements of use must be filed within 6 months from the date the USPTO issues a notice of allowance. Failure to submit the statement of use in a timely manner results in abandonment of the application.
The Amendment to Allege Use and the Statement of Use include the same information, and differ only as to the time when it is filed.
Source: U.S. Patent and Trademark Office.