There are three main situations when patent rights are terminated:
1. When the term expires, the invention patent right shall be maintained for 20 years from the date of application, and the utility model or design patent right shall be terminated from It shall be maintained for 10 years from the date of application and shall be terminated in accordance with the law.
2. Termination if the annual fee is not paid in accordance with regulations.
After the Patent Office issues a payment notice, notifying the patentee to pay the annual fee and late payment fees for the current year, the patentee has not paid or fully paid the annual fees and late payment fees for the current year at the expiration of the late payment period. Within two months from the expiration of the late payment period, but no earlier than one month at the earliest, the Patent Office shall issue a notice of patent termination and notify the patentee. If the patentee has not initiated the restoration procedure or the restoration has not been approved, the Patent Office shall Four months after the issuance of the termination notice, it will be registered and announced in the Patent Register and the Patent Gazette respectively. After that, the patent application file is stored in the invalid file database. The patent expiration date shall be the expiration date of the previous year.
3. The patentee voluntarily gives up the patent rights
So the answer is:
A. Patent term expires
C. The patentee failed to pay the annual fee as required
D. The patentee waives its patent rights in a written statement