• продлевать срок действия патента – extend the term of a patent
См. также: срок исполнения договора, срок исчисляется с, срок погашения облигации, срочный договор
The term of a patent is the maximum period during which it can be maintained in force. It is usually expressed in a number of years either starting from the filing date of the patent application or from the date of grant of the patent. (Wikipedia)
