Paperwork for the original TS licenses

HI Guys

we are looking to migrate from TS 2003 to RDS 2012, we have been following this from Microsoft

http://blogs.msdn.com/b/rds/archive/2009/03/06/migrating-a-windows-server-2003-license-server.aspx

however we have got down to 3.b where is says we need, Paper work for the original TS licenses

now the orginial environment was set up almost 10 years ago

can anyone explain to me what this is and where I get it ?

Chris