1. Failing to pay the annual fee as required;
2. The patentee waives his patent right in writing.
The termination of the patent right shall be registered and announced by the Patent Office. "Since his patent has expired, it is not protected by law. If someone imitates, he will sue and the court will not support it. But pay attention to the time, it is best to start production and sales after the registration announcement in the patent office, in case the other party finds your patent infringement.