Fortunately, under the US copyright law, your work is protected as soon as you write it. If you are only concerned about the work having a copyright, then your work is done because it already has one.
However, if you want to register the copyright, then you should decide if you want to do so as an individual or under your LLC. As others have indicated here, you are the owner of the content so it makes sense to register the copyright under your name. However, if there are additional details (like maybe you wrote the content about or for the LLC) then it may make more sense to register it under your company.
You should consult an IP attorney to learn more. Or, you may be interested innewest feature, Micro. For a low, flat-rate (usually $25) you can ask an attorney a legal question and receive a customized response in as little as 48 hours. Let us know if we can help!