I plucked this from their forums, since some folks here were saying its an always-online DRM and/or BioWare/EA should be making away with that:
Also, it was fixed.(Fernando Melo)
Why do I need to be logged in to play DLC or the game?
You don't - or are not supposed to need to be logged in. The system was designed such that after the first authorization you should be able to play offline, and it does do this for the overwhelming majority of players (based on data we see). As mentioned above however, there is a known issue which affects a very low number of players, and can be addressed either manually or with a beta tool we've provided (see below). But otherwise you should not need to login/re-authorize.
While the numbers are still low and manual/separate app fixes exist, there is also a patch for DAO that we had been working on to address this which was temporarily put on hold during the finaling period of DA2, and had already resumed since DA2's launch. We'll be looking into accelerating this now - however, at this point I don't have a timeframe I can offer yet.
Why am I still seeing issues?
Now that this new issue is resolved, if you still encounter issues with DLC authorization this is now 99% likely due to the previous known issue with the DA Updater service. Below are some links for solutions, including the beta tool I mentioned above.
http://social.bioware.com/forum/1/topic/58/index/5151520
http://social.bioware.com/forum/1/topic/58/index/81613
http://social.bioware.com/forum/1/topic/58/index/759141