legal ground
Article 44 of the Patent Law shall be terminated before the expiration of the time limit under any of the following circumstances: (1) Failing to pay the annual fee as required; (2) The patentee waives his patent right in writing. Article 47 An invalid patent right shall be regarded as nonexistent from the beginning. The decision to declare the patent right invalid has no retrospective effect on the patent infringement judgments and conciliation statements made and executed by the people's court before the patent right was declared invalid, the decisions on handling patent infringement disputes that have been performed or executed, and the patent licensing contracts and patent transfer contracts that have been performed. However, if the patentee's malice causes losses to others, it shall make compensation. If the patent infringement compensation, patent exploitation fee and patent transfer fee are not returned in accordance with the provisions of the preceding paragraph, which obviously violates the principle of fairness, they shall be returned in whole or in part.