Dead Space 3 on Xbox 360

Your misreading 'day 1' as '1 day' , it's implying you will have access to items released on the launch day, special items usually given by EA as an incentive for you to purchase the game early. The online activation code is also required to allow you access to EA servers to play the game online. This is done to hinder the reselling of the game and allows EA to sell online activation codes to people who buy preowned items whilst allowing them to still garner some monetary gain from their product.

So in direct response to your question, the items you receive you will have unlimited access too and (provided you have an Xbox live gold account) the online pass will allow you unlimited access to EA servers for as long as you want.