You can and you should register for attending LinuxDays and other conferences. Although registration is optional, it will help us estimate number of people coming and will get you some benefits as well. There is only one registration for all conferences and you can register for free but there are also other registration options that will let you support conferences financially.
Why register? Even with free registration you’ll get a badge with your name and bag full of swag. Among other things, bag will contain plush openSUSE chameleon called Geeko.
Next option is is supporters registration which costs €40. In comparison to free registration, you will get on top of everything unique gift (details of this gifts are highly classified and meant as a surprise) and opportunity to attend VIP dinner at Sunday evening with speakers and organizers.
Last option is registration as professional. Professionals will get on top of everything previously mentioned opportunity to attend feedback session with SUSE executive management team.
For those who will ask (independent of type of registration), organizers will try to provide possibility to buy a lunch nearby. So if you don’t want to be hungry during the conference, you can do something about it