You can visit the purchase page: http://www.vbulletin.com/en/purchases

Choose to buy a vBulletin 5 Connect license, under that you can install and run 3.8.7 the current patch level or higher. Basically you'll need to overwrite all your nulled files with the new legitimate ones... I would also submit a support ticket after purchasing, you can do so from the members area you'll receive access to after purchase - let them know you've made the purchase and need directions on how to replace the files and they'll let you know if there is anything in particular you need to do but far as I'm concerned should be a simple file replacement.

Other posts removed gentlemen, if he is asking how to obtain a valid license then he is doing the right thing so always post helpful links and info always be mindful of others and do not assume to know their intentions or how they are in a current situation.

Its good we have you super to make sense of that post as most thought he was asking how to get a nulled version

^ You know perspective is amazing, from my perspective I came into the thread and read it as "I'm using a nulled version but I want to do it right, how do I become licensed" but I see how some could have read it differently and we do that sometimes without realizing as well so no worries then I say, honest mistake now that we know ;).