If the patent is not renewed after its expiration, will the patent become invalid?

it is necessary to pay an annual fee for patents, and the limitation of protection for invention patents is 2 years, and that for utility model patents and appearance patents is 1 years. After the expiration, there is no need to have no protective effect. It is equivalent to the fact that this technology has been made public. So after the expiration, there is no need to renew the fee! Glad to answer for you!