Silver plated jewellery findings, such as pendant bails and chains, were developed to be a cheaper version of items that would otherwise be solid silver. Silver plating is commonly just a thin layer of silver applied over a base metal, such as copper or brass. This layer is thinner than silver-filled items and thus silver plated items will have a shorter lifetime as silver objects. Eventually, the plating will wear away exposing the base metal underneath, though this can still be quite attractive.
Some like the soft silver appearance of worn silver plate, and even the eventual brass or copper appearance when the plating is gone completely.
However, if you take care of your silver 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 silver plated items with care.