Gold plated jewellery findings, such as pendant bails and chains, were developed to be a cheaper version of items that would otherwise be solid gold. Gold plating is commonly just a thin layer of gold applied over a base metal, such as copper or silver. This layer is thinner than gold-filled items and thus gold plated items will have a shorter lifetime as gold objects. Eventually, the plating will wear away exposing the base metal underneath, though this can still be quite attractive.
Some like the soft gold appearance of worn gold plate, and even the eventual copper or silver appearance when the plating is gone completely.
However, if you take care of your gold plated item and never use any abrasive cleaning methods, you should get a long life from the item. A search of the internet will provide a number of solutions to cleaning your gold plated items with care.