I read in another post that with "single" licence I can install Obfuscator in 2 computers (home and work), if I would like to install in another one, do I need Team Pack?
In that case you can just buy another single license (if you buy 2 Single licenses at once, you automatically receive 10% volume discount).
What means "1 build machine, 4-5 machines"? is only possible to obfuscate in one main machine?
Yes, of course.
In "single" licence, what happens if I want to change the computer where Obfuscator is registered? Can I unregister it and register in a new one?
Yes, you can unregister it and register to a new one.