Do I need to have the letters LLC displayed in my logo if I am an LLC?

Your logo can be whatever you want. LLC is recommended to be placed on your letterhead, business cards and e mails.
LEGAL DISCLAIMER
Mr. Sarno is licensed to practice law in NJ and NY. His response here is not legal advice and does not create an attorney/ client relationship. The response is in the form of legal education and is intended to provide general information about the matter in question. Many times the questioner may leave out details which would make the reply unsuitable. Mr. Sarno strongly advises the questioner to confer with an attorney in their own state to acquire more information.

LLC is recommended to be placed so as to not confuse.

I agree with the observations of Mr. Sarno.

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Normally, the best practice would be to have the LLC appear very small in the logo - as it's part of the legal name of the business, it should be there.

Disclaimer: This answer is provided as a public service and as a general response to a general question, it is not meant, and should not be relied upon as specific legal advice, nor does it create an attorney-client relationship.