Battery registration was introduced by BMW to ensure better battery life and lower chances of electrical issues.
However, if your BMW is older than 2002, you don't need to do anything. Since you have a 2008 model, you will need to register the battery every time.
There are very simple tools and scanners you need to use to register your battery. Try Autel MaxiDAS DS808, as it can help you easily register your battery, even if its not an original. Carly for BMW, is also a cheaper option but it has limited functions, which might be okay for the everyday user.
Foxwell for BMW NT510 is probably the simplest scanner you can use, but it only works with an original battery.