Section 8 Declaration of Continued Use

a sworn statement, filed by the owner of a registration that the mark is in use in commerce. Section 8 of the Trademark Act, 15 U.S.C. §1058. It must be filed by the current owner of the registration and the USPTO must receive it during the following time periods: 1) At the end of the 6th year after the date of registration (or the date of publication under 15 U.S.C. §1062(c) for registrations issued under the Acts of 1905 or 1881 that have claimed the benefits of the Act of 1946),
AND

2) At the end of each successive 10-year period after the date of registration. There is a six-month grace period. If these rules and deadlines are not met, the USPTO will cancel the registration.

-- see File a § 8 Declaration 

Context: Trademark