All photofinishers tested here use light-sensitive photographic paper to make their prints, just as photofinishers have been doing for decades; but now, instead of shining light through a negative onto the photographic paper, the light is generated by a computer according to information in the digital image you give them. Thus the prints produced by this method, on photographic paper, should last as long as traditional prints produced from film. (Home photo printers typically use inkjet, dye sublimation, or laser printing technology.)
The quality of a print is influenced by the quality of the photographic paper and the photofinishing (which may include digital image processing, such as sharpening).