| name | The store's name, eg 'AppleAppStore'. |
| a | The store implementation, or null if running on an unsupported platform. |
Register a store implementation along with its name.
Names are used to determine which store-specific ID to use when interacting with a billing system; eg a store with name 'AppleAppStore' would receive the 'AppleAppStore' store-specific product IDs that the App developer specifies when building their IAP configuration.