Regulation 6 of PECR covers storing information on, or accessing information from, a subscriber's or user's terminal equipment. The rule is technology-neutral: cookies, tracking pixels, tags, scripts, local storage, software development kits, device fingerprinting, and automatically emitted device information can all be in scope.
For a non-exempt purpose, give clear and comprehensive information and obtain UK GDPR-standard consent before storage or access begins. Consent must be freely given, specific, informed, and indicated by an unambiguous positive action. Continuing to browse, silence, inactivity, or a pre-enabled control is not enough.
Classify each purpose separately. If one technology serves an exempt purpose and advertising or another non-exempt purpose, consent is still required for the non-exempt purpose. Calling a technology 'essential' or 'analytics' does not determine the result.