How to integrate different vbulletin sites?

[helalmail]

How to integrate different vbulletin sites for user log in
so as the user will log in one time only for the different sites

I have 3 licenses, making different sites. I want the user after log in in any of them , then moves to the other site, he will stay logged in

[Raeven]

I guess for that you need one Databank for all 3 sites, so you have the accounts there too. And then you need a cookie for that, i guess.