TRADEMARK LICENSE AGREEMENT

Exhibit 10.3

TRADEMARK LICENSE AGREEMENT

THIS TRADEMARK LICENSE AGREEMENT (the “ Agreement ”), made as of the 20th day of November, 2006, is by and among Constellation Energy Partners LLC, a Delaware limited liability company (the “ Company ”), and Constellation Energy Group, Inc., a Maryland corporation (“ Constellation ”).

WHEREAS, subject to the terms hereof, Constellation desires to grant the Company, and the Company desires to take from Constellation, a limited license to use certain marks in connection with the Company’s business.

NOW, THEREFORE, in consideration of the mutual covenants herein and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto (each, a “ Party ” and together, the “ Parties ”) agree as follows:

ARTICLE 1

DEFINITIONS

Section 1.1 Defined Terms . Capitalized terms used, but not defined herein, shall have the meanings given them in the LLC Agreement. As used in this Agreement, the following terms shall have the respective meanings set forth below:

“ Affiliate ” means, with respect to a Person, any other Person controlling, controlled by or under common control with such Person.

“ Agreement ” means this Agreement, as it may be amended from time to time.

“ Business Day ” means any day that is not a Saturday, Sunday or day on which banks are authorized by law to close in the States of Maryland or Texas.

“ Closing Date ” means the date of the closing of the initial public offering, pursuant to the Prospectus, of Common Units.

“ Company ” has the meaning set forth in the above preamble.

“ Conflicts Committee ” has the meaning given such term in the LLC Agreement.

“ Constellation ” has the meaning set forth in the above preamble.

“ LLC Agreement ” means the Second Amended and Restated Operating Agreement of the Company, dated as of the Closing Date, as such agreement is in effect on the Closing Date, to which reference is hereby made for all purposes of this Agreement. An amendment or modification to the LLC Agreement subsequent to the Closing Date shall be given effect for the purposes of this Agreement only if it has received the approval that would be required pursuant to Section 4.10 hereof if such amendment or modification were an amendment or modification of this Agreement.

“ Marks ” means all trademarks, tradenames, logos and service marks identified on Exhibit A .

“ Person ” means any individual, corporation, partnership, business trust, limited liability company, joint venture, association, joint-stock company, trust, unincorporated organization, government or any agency or political subdivision thereof or any other entity.

“ Proceedings ” means all proceedings, actions, claims, suits and notices of investigations by or before any arbitrator or Governmental Authority.

“ Prospectus ” means the final prospectus, dated November 15, 2006, relating to the initial public offering of common units representing Class B limited liability company interests in the Company, as filed with Securities and Exchange Commission pursuant to Rule 424(b) under the Securities Act of 1933.

“ Term ” means the period from the Closing Date through the date upon which the right of the holder or holders of the Class A Units to elect Class A Managers pursuant to Section 11.8(e) of the LLC Agreement is terminated.

“ Third Party ” means any Person other than the Company or Constellation or any of their respective Affiliates.

Section 1.2 Other Definitions . Words not otherwise defined herein that have well-known and generally accepted technical or trade meanings in the oil and gas industry are used herein in accordance with such recognized meanings.

Section 1.3 Construction . As used in this Agreement, unless expressly stated otherwise, references to “includes” and its derivatives mean “includes, but is not limited to,” and corresponding derivative expressions. Unless otherwise specified, all references in this Agreement to “Sections” and “Exhibits” are references to the corresponding sections in and exhibits attached to this Agreement; all such exhibits are incorporated herein by reference.

ARTICLE 2

Intellectual Property License

Section 2.1 Limited License . Subject to the terms and conditions herein, Constellation hereby grants to the Company the limited right and license to use the Marks solely in connection with the Company’s businesses and the services performed therewith within the United States during the Term and for a period of six (6) months thereafter.

Section 2.2 Restrictions on Marks . In order to ensure the quality of uses under the Marks, and to protect the goodwill of the Marks, the Company agrees as follows:

(a) The Company will only use the Marks in formats approved by Constellation and only in strict association with the Company’s businesses and the services performed therewith;

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(b) Prior to publishing any new format or appearance of the Marks or the advertising or promotional materials, the Company shall first provide such format, appearance or materials to Constellation for its approval. If Constellation does not inform the Company in writing within fourteen (14) days from the date of the receipt of such new format, appearance or materials that such new format, appearance or materials is acceptable, then such new format, appearance or materials shall be deemed to be unacceptable and disapproved by Constellation. Constellation may withhold approval of any proposed changes to the format, appearance or materials that the Company propose to use in Constellation’s sole discretion; and

(c) The Company shall not, without the prior approval of Constellation, use any other trademarks, service marks, trade names or logos in connection with the Marks or use the Marks or any trademark or service mark confusingly similar to the Marks after the termination of this Agreement. The Company will not use the Marks in such a manner so as to impair the validity or enforceability of, or in any way disparage or dilute, the Marks.

Section 2.3 Ownership . Constellation shall own all right, title and interest, including all goodwill relating thereto, in and to the Marks, and all trademark rights embodied therein shall at all times be solely vested in Constellation. The Company shall have no right, title, interest or claim of ownership in the Marks, except for the limited license granted in this Agreement. All use of the Marks shall inure to the benefit of Constellation. The Company agrees that it will not attack the title of Constellation in and to the Marks.

Section 2.4 Estoppel . Nothing in this Agreement shall be construed as conferring by implication, estoppel or otherwise upon the Company (a) any license or other right under the intellectual property rights of Constellation other than the limited license granted herein to the Marks as set forth expressly herein or (b) any license rights ot