If you want to sell pseudoephedrine, your org has to "self certify", keep a logbook purchasers have to sign, require ID, enforce the purchase limits, train employees, etc. But, the logbook doesn't go anywhere unless some investigation or audit prompts that. So, if you're a really determined cooker, you can still go to a bunch of different stores...though you're leaving a paper trail. And some big brands might cross-check and have an org-wide electronic log book.