After more than a month of the original release date, the Pokémon Bank app finally makes its debut on the 3DS’ eShop today. If you are unfamiliar with the app, the Bank lets players save and manage up to 3000 Pokémon.
If you download and activate the free app before March 14, you will get a 30-day trial. After the trial expires, or if you download and activate the app after March 14, an annual subscription fee of $4.99 will be required.
Pokémon Bank will also let you download the Poké Transporter, an app that lets users transfer their pocket monsters from Black, Black 2, White, and White 2.
[Source]: Nintendo eShop.