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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Development Plan milestones as set forth in Section 6.2 and the Development Plan. 4.6. Personnel Matters. Sekisui shall offer employment to four Qualigen sales representatives to become employees of Sekisui with primary responsibility for the sale of the Products, and Qualigen hereby consents to and permits such employment. Such offers of employment are subject to Sekisui's employment policies, including the successful completion of customary background checks, and are not a guarantee of ongoing employment. Upon the expiration or termination of the Term (other than in connection with a Sale Transaction in which Sekisui acquires Qualigen), Sekisui shall cooperate in permitting Qualigen to offer to rehire any Sekisui sales representatives who are primarily responsible for selling the Products. A sales person "primarily responsible for selling the Products" is one that spends more than half of his or her time and receives more than half of his or her commission based compensation based on sales of the Products. 4.7. Invoice Terms. Sekisui shall pay for each Product sold by Qualigen within 30 days after Sekisui has received the applicable invoice from Qualigen. 4.8. Marketing Claims. Sekisui covenants to Qualigen that Sekisui will not make any written or oral representation or marketing claim (either formal or informal) about any Product's capabilities or characteristics other than those representations and claims that are fully and directly supported by factual materials provided by Qualigen to Sekisui. Sekisui shall not make any false or misleading representations to customers or others regarding Qualigen or the Products. Sekisui shall not make any representations, warranties or guarantees with respect to the specifications, features or capabilities of the Products that are not contained within Qualigen's documentation accompanying the Products or Qualigen's literature describing the Products, including Qualigen's standard limited warranty and disclaimers. 7 Source: RITTER PHARMACEUTICALS INC, S-4/A, 3/13/2020 4.9. Taxes. Qualigen's stated Product prices do not include any foreign, federal, state or local sales taxes that may be applicable to the Products, but in the event that such sales taxes are applicable and Qualigen has the legal obligation to collect such sales taxes (or are sales taxes imposed on a seller), Qualigen shall be entitled to add to its invoice the amount of such sales taxes and Sekisui shall pay such amount unless Sekisui provides Qualigen with a valid tax exemption certificate authorized by the appropriate taxing authority. As between the Parties, all customs duties shall be the responsibility of Sekisui, and all duty expenses will be included as an element of COGS as referenced in Exhibit A and will be included as part of the Actual Margin True-Up as defined in Exhibit D. The parties agree to cooperate with one another and use reasonable efforts to avoid or reduce tax withholding or similar obligations in respect of Financing Payments, Product purchase payments, and other payments made by Sekisui to Qualigen under this Agreement. To the extent Sekisui is required to withhold taxes on any payment to Qualigen, Sekisui shall pay the amounts of such taxes to the proper governmental authority in a timely manner and promptly transmit to Qualigen evidence of such payment and/or an official tax certificate, or such other evidence as Qualigen may reasonably request, to establish that such taxes have been paid. Qualigen shall provide Sekisui any tax forms that may be reasonably necessary in order for Sekisui to not withhold tax or to withhold tax at a reduced rate under an applicable bilateral income tax treaty. Each Party shall provide the other with reasonable assistance to enable the recovery, as permitted by applicable law, of withholding taxes, value added taxes, or similar obligations resulting from payments made under this Agreement, such recovery to be for the benefit of the Party bearing such withholding tax or value added tax. 4.9.1. Medical Device Tax. The party responsible for paying any applicable medical device excise tax pursuant to Section 4191 of the U.S. Internal Revenue Code or any successor thereto will be as determined under such tax provisions. If any, such medical device excise tax will be treated as a cost element to be included in COGS as referenced in Exhibit A. 4.10. Interest. Accrual and payment of interest shall not be deemed to excuse or cure breaches of contract arising from late payment or nonpayment. Cumulative with and not exclusive of any and all other available remedies, payments that are more than 30 days past due hereunder, and which are not otherwise subject to a good faith dispute, shall accrue interest, from the due date until paid,
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Extract the exact clause related to "Irrevocable Or Perpetual License" from the excerpt above.