"The registration is valid as long as you timely file all post registration maintenance documents. You must file a “Declaration of Use under Section 8” between the fifth and sixth year following registration. In addition, you must file a combined “Declaration of Use and Application for Renewal under Sections 8 and 9” between the ninth and tenth year after registration, and every 10 years thereafter. If these documents are not timely filed, your registration will be cancelled and cannot be revived or reinstated." - http://www.uspto.gov/faq/trademarks.jsp#_Toc275426707
I think what you're talking about with:
deals with patents, as those have to be used within fourteen years. Although, I'm not entirely sure, the only thing I know about the matter is what I linked here.