Well, you probably could use the software but then - you have no copyright option in the software used bought from another person. Buying Music Creator 6 or whatever would give about the same thing (except the version is cut down), but if you are not recording a band with several tracks at once, and only two tracks at a time and just starting out, it probably would be cheaper and work as long as you have a computer that can use it (like Windows 7 - 8 maybe Vista).
A lot of us used Music Creator (whatever version 4 is my latest one I used and bought until Sonar) and had fun using it. Learning it which correlates into using a Sonar better version and no one had to worry about registration, and the biggest worry of all - always needing a patch usually with any software bought nowadays.
At say what - $40 - there's a lot that can be done with Music Creator whatever version - say 6 for the latest one.
And or Sonar Essential which would be even better and not much more perhaps (have to check prices).
The copyright option is for your music, not the software, as the owner and creator of the music. (the software is also copyrighted also though as the software from the company that made it - just like you make your music).
If he registered the software than any music produced in the software would actually be in his name, and not your name.