One of the biggest worries with PDF QR codes is expiry, the fear that a code printed on thousands of flyers will one day stop working. The good news: codes don't expire on their own. Understanding why some seem to expire shows you how to make one that lasts forever.
QR Codes Don't Expire By Nature
A QR code is just a pattern encoding data. The pattern never degrades or times out. When people say a code "expired," what actually stopped working is the destination it points to, not the code itself.
Why Some Codes Seem to Expire
Dynamic codes route through a provider's service. If that service is a free trial that ends, or the account lapses, the redirect dies and the code appears broken. The code is fine; the service behind it stopped. This is the usual cause of "expiry."
The No-Expiration Recipe
Make a static code that encodes your PDF's link directly, with no provider redirect in between. As long as the PDF stays at that link, the code works indefinitely. Host the file somewhere stable and generate the code with a PDF QR generator.
Keeping the Destination Alive
Since the only thing that can "break" is the link, keep your hosted PDF at a stable address and don't delete or move it. If you must keep the option to change it, accept that a dynamic code's longevity depends on maintaining that service.
FAQ
Common questions are answered in the FAQ section below.