In case you didn't already know this from watching "Breaking Bad," pharmacies track your pseudoephedrine purchases because the drug is commonly used to make meth.
That's why you get carded when you buy cold meds. It isn't enough for pharmacies to limit customers' pseudoephedrine purchases at a single store because meth-producers could just hop from store to store to buy the amounts they need. The driver's license tracking system arguably makes it harder for producers to get their hands on the drug.
This week, the Fifth Circuit Court of Appeals ruled that those pseudoephedrine transaction logs are nontestimonial business records, which means that it's pretty easy for the government to introduce the logs at trial.