Do you have to use the cd to play?

Do you have to use the cd to play?

me and my sister have to different computers, and i wanted to split the cost with her and let her play on her computer and i play on my computer, but that will be pretty hard if we have to share the cd.
and ideas?? or well at least let me know if you have to have the cd.
please and thanks!

 

ok thank you.

 

I think this is the obvious answer of this question.