Apple will allow you to place your iTunes account on 5 computers .
That means you can duplicate your music and account on these computers.
However you will need to “authorize” these computers with your Apple ID
If you have stopped using a computer , don’t forget to “deauthorize” that computer
Once a year you can “deauthorize” all computers ( whether you have them or not) and then ” authorize” the computers you are using.
Remember if you cannot find your Apple ID , here is a link to help you.