buying VB from someone,and purchasing a new licence question

[daabomb2002]

If someone sells me their vbulletin forum,and i wanted to transfer it to my server,how would I do this and then buy a new licence for myself?

Does the person selling me the forum just have to backup their Mysql database,then all I have to do is load this database onto my server,then will vbulletin automatically be installed? Then do i just purchase a licence from here?

If not,what is the process or transfering vbulletin from One server to another without losing any posts the forum members have made? Do i have to have vbulletin installed on my server first,then import the mysql database? what if the person is using a lower version of vbulletin and i use the newer version?

And once I have got vbulletin installed,how do I apply a licence that I will purchase from here into vbulletin?

[HabboHut]

If you want to purchase a new licence straight away anyway, just install vBulletin on your server with your licence copy, and grab a database dump from the other server. Import that into your database through phpMyAdmin, and you're away.