本协议有效期从2004年五月1日至2007年12月31日。
本合同自生效之日起_______年有效，有效期满后合同将自动失效。
The Contract shall be in force for 5 years from the effective date of the Contract. After the expiration f its term of validity, the contract shall automatically become null and void.
第一阶段为期三年（第一年至第三年），为核心测试阶段。
b) the second phase of two (2) CALENDAR YEARS (the fourth CALENDAR YEARS throughthe fifth CALENDAR YEARS ) for PILOT DEVELOPMENT.
当意大利方面依据法律批准了和中国的该服务时，本协议视为生效。
如合同自签字之日起经过六个月仍不能生效，则双方有权取消本合同。
If the Contract cannot come into force within 6 (six) months after the date of signing the Contract, both parties shall have the right to cancel the Contract.
本协议自中国商务部批准之日起生效。
再如：The AGREEMENT shall be deemed to have come into effect on the date when Italy has passed the LAW to cooperate with China concerning SERVICES.
本合同生效日是中华人民共和国商务部批准之日。
例2在合同中单列一个生效和有效期条款，比如：
This AGREEMENT shall commence with effect from 2nd October 2005(“EFFFECTIVE DATE”) and shall continue until 2nd October 2010 unless terminated earlier in accordance with its terms and conditions.
本协议生效日期为2000年11月30日，但如果届时未能生效，除非各方另有约定，本协议自动解除，各方互不承担责任。
采购协议的生效视另一个事件是否发生。为避免合同签订后其效力处于不确定的状态拖得太长，可在合同中约定，在某种条件下，合同永不生效，比如：
This AGREEMENT shall never take effect provided that PARTY B cannot get the approval from the competent authority within thirty (30) days after the signature of this AGREEMENT.
甲方有权在任何时候向乙方发出通知终止本协议。
This AGREEMENT shall come into effect on［the date of execution］, and shall continue in force until terminated by either PARTY giving to the other not less than days notice expiring on［termination date］.
本合同自2005年10月2日起生效，除非根据本合同约定条款终止，有效期至2010年10月2日。
二、在所附条件成立时为合同生效基准日
合同生效除了以具体的日期表述外，还可以约定以某个事件的发生或不发生作为其生效起点，相当于附条件，只有在所附条件成立时合同才生效，比如在一个中外合资合同中：
The AGREEMENT shall take affect upon the approval from the Ministry of Commerce of the People’s Republic of China.
The Effective date and Duration Provision of Contract
一、以合同的生效日作为计算基准日
合同的生效日期在合同中非常重要，合同有效期一般都是以合同生效日作为基准日。合同中约定的当事人的权利义务享有或承担的起始日期都是以合同的生效日作为计算基准日。
如：
The BUYER shall make an advance payment of twenty million US Dollars ($2,000,000.00) to the SELLER within fifteen (15) days after the EFFECTIVE DATE of this PURCHASE and SALES CONTRACT.
买方在采购合同生效之日起15个工作日内向卖方支付200万美元的预付款。
再如：The CONTRACTOR shall complete WORK within six (6) months after the EFFECTIVE DATE of this DESIGN CONTRACT.
承包商自本设计合同生效之日起六个月内完成工作。
本合同自2007年11月7日生效，有效期为三年。
为避免争议，一般在草拟合同时直接在合同中约定生效日，这种约定主要有以下几种表达方式：
例1在定义部分，就“生效日”进行定义，如：
EFFECTIVE DATE means the date on which the CONTRACT, after it is signed, be approved by the Ministry of Commerce of the People s Republic of China.
第二阶段为两年（第四年至第五年），为实验开发阶段。
一方通知对方随时终止合同的约定：
This AGREEMENT shall take effect as of the date first above written and shall maintain in full force and effect until earlier termination by PARTY A in accordance with the terms and conditions herein.
This AGREEMENT shall take effect from the EFFECTIVE DATE provided that if the EEFFECITVE DATE has not occurred by 30 November 2000, this AGREEMENT shall (unlessthe PARTIES agree otherwise) automatically terminate and each of the PARTIES hereto shall be released from any further obligations hereunder。
本合同有效期包括勘探期、开发期和生产期：
The exploration period, beginning on COMMENCEMENT DATE, shall be divided into two (2) phases and shall consist of five (5) consecutive CALENDAR YEARS, unless otherwise required.
合同签订后30日内乙方没有获得自己政府批准，则本协议自动解除。
三、关于合同有效期的持续期间
合同有效期的约定方式比较固定，通常为：
1）从生效日到某个具体日期；
（2）一个固定期间；（
3）一方可以通过通知随时终止。
例1明确约定一个具体日期。
This AGREEMENT shall become effective as of 1 May, 2004 and remain valid until 31st, December 2007.
开发期从起始日连续5年，分为两个阶段，除非另有约定：
The two (2) phases shall be as follows:两个阶段为：
a) the first phase of three (3) CALENDAR YEARS (the first CALENDAR YEAR through the third CALENDAR YEAR) for core testing;
本专利许可协议有效期从生效日起至专利权有效期内的期间，为期15年，只要技术权利得到许可，而且该技术权利不涉及专利权问题。
.以专利的有效期结百度文库作为合同有效期最后一日。在合同中约定一个固定期间，作为合同有效期。如：
The AGREEMENT shall remain in effect for a period of five (5) years from the EFFECTIVE DATE, unless earlier terminated under the provisions hereunder.
本协议从生效之日起有效期为5年，除非依据本协议另有约定提前解除。
在一个勘探开发合同中：
The term of the CONTRACT shall include an exploration period, a development period and a production period:
本协议于上述日期生效，在甲方依据本协议约定通知提前终止之前，应一直保持效力。
PARTY A shall have the right to terminate this AGREEMENT at any time in its own discretion by serving a notice to PARTY B.
The term of this PATENT LICENSE AGREEMENT shall be from the EFFECTIVE DATE to the full end of the term or terms for which PATENT RIGHTS have not expired or, if only TECHNOLOGY RIGHTS are licensed and no PATENT RIGHTS are applicable, for a term of 15 years
本合同的有效期从合同生效日起算共_____年。
The Contract shall be valid for a period of ____ years from the Date of Effectiveness of the Contract.
如：This AGREEMENT shall commence on 7th, November 2007(“EFFECTIVE DATE”) and shall maintain in full force and effect for three(3) years after the EFFECTIVE DATE。
本协议应于日起生效，应一直有效至任何一方提前至少日通知另一方终止协议，在此情形下，协议应于［终止日期］终止。
以下是一条典型的期限条款，其中对于终止日期提供了多种选择：
This AGREEMENT shall［come］［be deemed to have come］into effect on［insert date］［the date of execution］, and, unless terminated earlier in accordance with clause X, shall continue in force until