Do you have to use a trademark under USPTO?
Your question appears to ask whether you can make use of a trademark whether it is registered at the USPTO or not. This is a common question with no simple answer. This is why.
The federal registration of a trademark by the United State Patent Office is not mandatory per se. However, doing so avoids a tremendous amount of problems ranging from infringement to dilution. It also safeguards the trademark from being abused for purposes other than what it is intended to represent. Moreover, registering the trademark at the USPTO protects what the mark is intended to represent as well. It basically freezes its use at a level where whoever tries to misuse it will encounter serious consequences at no expense to the registrant of the mark. Therefore, while it is allowed to use a trademark that is not registered by USPTO, any kind of intellectual property is protected already by Congress under 15 Title 1055 and the user of the trademark, if it is used with ulterior motives, will find dire consequences.
Anyone who finds out that someone has been using their already published intellectual property in a tangible form (poem, song, motto, name, logo, etc that is 100% unique and reunites specific requirements, can appeal to Title 17, Chapter 1, § 102 of the USC under Copyright Law which states that
Copyright protection subsists, in accordance with this title, in original works of authorship fixed in any tangible medium of expression..... Works of authorship include the following categories:(1) literary works;(2) musical works, including any accompanying words;(3) dramatic works, including any accompanying music;(4) pantomimes and choreographic works;(5) pictorial, graphic, and sculptural works;(6) motion pictures and other audiovisual works;(7) sound recordings; and(8) architectural works.