Renewal of consent
Every 12 months, the consent should be renewed upon the user’s first visit to the site. It is a GDPR cookie compliance requirement. The General Data Protection Regulation was adopted by both the European Parliament and the European Council in April of 2016 and came into force on May 25, 2018. GDPR is current legislation but the ePrivacy Regulation is underway.
More information on GDPR and cookies:
Why internet cookies are almost never all right? 