It depends on your state. Some states require you to include "LLC" every time. The easy way around that is to get an Assumed Name or DBA. You won't have to include LLC every time, but you will have to pay a little bit extra to get an assumed name if you don't want to include LLC at the end of your company name. If you're going for the credibility strategy, a company named ACME Publishing, LLC sounds very good. You look like a professional rather than a hobbyist with an LLC in your business name.