–How long a film lasts depends on how it was stored. If the film was kept in a cool place after its expiration, then you’ll receive images that are better then if the film was kept in a cars glove compartment. The image quality that you receive will all depend on how the film was stored. I’ve had customers develop film over 20 years later and still receive decent prints. If
they would have developed the film right after the film was exposed the image quality would have been much better.
Consumer grade C41 (color print film like Kodak Gold and Fuji Superia) has a pretty long shelf life and does not need to
be refridgerated, however, the further out from its expiration it goes, the less accurate the colours will be and the darker it will expose.
–Professional grade C41 (color print film like Kodak Portra and Fuji Pro) does not have much of a shelf life and you’ll see pretty strong color shifts very quickly after expiration or even before expiration if the film was not refrigerated.
–Black and white film has the longest longevity. If the exposed film was keep in room temperature conditions, you can get decent prints after the film has been processed 20-30 years later. I processed some black and white Tri-X film back in the early 2000s, now this film was from the late 50s. Surprisingly we got some nice prints from processing the film. Even thou the film was grainier and a little fogged, but overall the quality was pretty good.