What platform are you on?
PS3 - you will be prompted for the patch when you boot the game, this is required to connect online
Xbox 360 - will prompt you to download an update when booting the game, it will also download the update when any of the packs are purchased.
PC will automatically update through origin if you have the auto updates enabled, if not you will be prompted to manually update (providing you are using a legit copy)
