system: You are a contract-analysis assistant performing a span-extraction task. You are given an excerpt from a commercial contract and the name of a clause type to locate within it.

Return the exact text of the requested clause, copied verbatim from the excerpt — identical wording and punctuation, with no paraphrasing, summarising, explanation, or added commentary.

The excerpt is one window of a much longer contract and often will not contain the requested clause. If the requested clause does not appear in this excerpt, respond with exactly: Not found.

Output only the extracted clause text, or the exact string `Not found.` — nothing else.

user: Contract excerpt:
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further force and effect and Aimmune shall cease Developing, Commercializing, Manufacturing and Packaging and Labeling such Product in and for all applicable countries; provided, that Aimmune and its Affiliates will be entitled, during the period 40 Source: AIMMUNE THERAPEUTICS, INC., 8-K, 2/5/2020 ending on the last day of the [***] following the effective date of such termination, to sell any inventory of Product affected by such termination that remains on hand as of the effective date of the termination, so long as Aimmune pays to Xencor all amounts payable hereunder (including milestones) applicable to said subsequent sales, as applicable, in accordance with the terms and conditions set forth in this Agreement and otherwise complies with the terms set forth in this Agreement. 14.1.2 Aimmune hereby grants to Xencor an exclusive license under and with respect to Aimmune Patents, and a non-exclusive license under and with respect to Aimmune Know-How, in each case, where such license is an irrevocable, perpetual, royalty-bearing license, with the right to sublicense, to Develop, Manufacture and Commercialize the Product(s), as the Product(s) exist as of the effective date of such termination, or optimized versions thereof that are Products. For clarity, upon the termination of this Agreement, as consideration for such licenses granted under this Section 14.1.2, Xencor shall [***], and Xencor shall be responsible for [***]; provided further that Xencor shall have the right to terminate such license and forgo paying such royalties at its sole discretion upon written notice to Aimmune. 14.2 Assignments. Upon the termination of this Agreement, Aimmune will promptly, in each case within [***] ([***]) days thereafter: (a) assign to Xencor, [***], all of Aimmune's right, title and interest in and to any agreements (or portions thereof) between Aimmune and Third Parties that relate to the Development, Commercialization or Manufacture of the Product, where such assignment is permitted without charge to Aimmune or its Affiliates and where Xencor shall assume all future payments due under any agreement assigned pursuant to this subsection; (b) assign to Xencor, [***], and subject to the execution of a standard trademark license between the Parties prior to such assignment, all of Aimmune's right, title and interest in and to any (i) Promotional Materials, (ii) copyrights and trademarks (including the Product Trademarks and Product Trade Dress), including any goodwill associated therewith, and any registrations and design patents for the foregoing, and (iii) any internet domain name registrations for such trademarks and slogans, all to the extent solely related to the Product; provided, however, in the event Xencor exercises such right to have assigned such Promotional Materials, Aimmune shall grant, and hereby does grant, a royalty-free right and license to any housemarks, trademarks, names and logos of Aimmune contained therein for a period of [***] ([***]) months in order to use such Promotional Materials solely in connection with the Commercialization of the Product; (c) assign to Xencor, [***], the management and continued performance of any Clinical Trials for the Product ongoing hereunder as of the effective date of such termination in respect of which Xencor shall assume full financial responsibility from and after the effective date of such termination; (d) transfer to Xencor all of Aimmune's right, title and interest in and to any and all regulatory filings, Regulatory Approvals and other Regulatory Materials for the Product; 41 Source: AIMMUNE THERAPEUTICS, INC., 8-K, 2/5/2020 (e) transfer to Xencor all of Aimmune's right, title and interest in and to any and all Development-related data and Commercialization Data Controlled by Aimmune for the Product; and (f) provide a copy of (i) the material tangible embodiments of the foregoing and (ii) any other material books, records, files and documents Controlled by Aimmune solely to the extent related to the Product and which may be redacted to exclude Confidential Information of Aimmune; provided, however, that to the extent that any agreement or other asset described in this Section 14.2 is not assignable by Aimmune (whether because such agreement or asset is explicitly non-assignable or because the Third Party consent required for such assignment is not obtained), then such agreement or other asset will not be assigned, and upon the request of Xencor, Aimmune will take such steps as may be reasonably necessary to allow Xencor to obtain and to enjoy the benefits of such agreement or other asset. For purposes of clarity, (1) [***] and (2) to the extent Xencor requests [***]. 14.3 Disclosure and Delivery. Upon the termination of this Agreement, Aimmune will promptly transfer to Xencor copies of any physical embodiment
"""

Extract the exact clause related to "Irrevocable Or Perpetual License" from the excerpt above.

assistant: Aimmune hereby grants to Xencor an exclusive license under and with respect to Aimmune Patents, and a non-exclusive license under and with respect to Aimmune Know-How, in each case, where such license is an irrevocable, perpetual, royalty-bearing license, with the right to sublicense, to Develop, Manufacture and Commercialize the Product(s), as the Product(s) exist as of the effective date of such termination, or optimized versions thereof that are Products.