|年金||annual fee, annuity, annual tax
|5年次年金を払う||to pay the fifth annuity
|納付||payment of the annuity|
The seventh annuity was paid on 〜,and the patent is in force if all future annuities are paid, the patent will be effective until 〜i.e., 20 years from the filing date.
The patent expired because the sixth and subsequent annuities were not paid →特許料