The short answer is no - you don't NEED an NBS ID to use Source, BUT you will get a better experience if you log in with your NBS ID.
Your NBS ID will allow you to save favourites and access the Help areas where you can check knowledge base articles, contact the support team and in the future participate in forums and communities.
Additionally, NBS Source brings you direct links between your NBS Chorus subscription and NBS Source to really harness the power of connected specification data and manufacturer content.
If you haven't got an NBS ID - don't worry. Just visit theNBS.com/login and register for an account - it only takes a couple of minutes.