EVE PLEX can be traded or sold between players on the in game market. It can also be used in the New Eden Store to upgrade your account to get Omega Clone state, purchase virtual goods, and activate other account services.
7430 PLEX is valued at $0.0336 Cents each. This package is only for serious players who need to generate serious amounts of ISK in game or wish to set their account to Omega for 14 months. This will give you lots of PLEX to sell for ISK. This is enough to set your clone at Omega for 420 days and have 430 left over.
To use PLEX in the New Eden Store, It must be placed in your PLEX Vault. The Vault is a secure location in your inventory, shared across all characters on your account, where it can be placed for use in the New Eden Store. You can find the Vault in your inventory in the Neocom (Upper left corner of your game screen).