Blood Lyf can tell Meta which public pages were opened, so we can see whether ads are reaching people. This does not include your name, phone, address, test names, reports, booking numbers, or payment details. The site works the same if you say no.
If measurement was already turned on during this visit, the Meta script and any cookie already saved stay in this browser until you leave or the cookie expires. Turning it off stops any further page measurements.
Allow is the only action that turns measurement on. No thanks, closing the question, or leaving it counts as no. You can change this later in Profile, under Advertising measurement.