Last year, the CA/Browser Forum announced that, starting September 1, 2020, certificate authorities (CAs) may only issue SSL certificates with a maximum validity period of 397 days.
As a result of this change, the Software Store advises customers to renew their certificates no more than 45 days in advance of the certificate's expiration date. This will ensure the customer does not lose time on the certificate by renewing early.
See One Year Certs for background information on the change.