History of the band -
In early 1985, Dr. Dag Hallberg applied for a patent for the Swedish Adjustable Gastric Band (SAGB) within Scandinavian countries. In late March, Dr. Hallberg presented his idea of the "balloon band" at the Swedish Surgical Society and started to use the SAGB in a controlled series of 50 procedures. During this time, laparoscopic surgery was not common and Dr. Hallberg and his assistant, Dr. Peter Forsell, started performing the open technique to implant the SAGB.
In 1992, Dr. Forsell was in contact with different surgeons in Switzerland, Italy and Germany who began to implant the SAGB with the laparoscopic technique. Dr. Forsell fully owned the patent at this time. In 1994, Dr. Forsell presented the SAGB at an international workshop for bariatric surgery in Sweden, and from then on, the SAGB started to be implanted laparoscopically. During this time, the SAGB was manufactured by a Swedish company, ATOS Medical.
So i'd guess unless you have some sort of mecanical failure the band will function for a long time.