Licenses under this subchapter shall be issued for a period not exceeding fifty years. Each such license shall be conditioned upon acceptance by the licensee of all of the terms and conditions of this chapter and such further conditions, if any, as the Commission shall prescribe in conformity with this chapter, which said terms and conditions and the acceptance thereof shall be expressed in said license. Licenses may be revoked only for the reasons and in the manner prescribed under the provisions of this chapter, and may be altered or surrendered only upon mutual agreement between the licensee and the Commission after thirty days’ public notice.