Can't register Cubase LE5

I am trying to get Cubase Le5 to register on my new iMac. I am running OSX.
I purchased my Zoom H4n last year but I NEVER USED THE SOFTWARE. However, I did install it on my PC. Once again, IN EVER USED IT. I am now ready to learn Cubase LE5 on my Mac system. Please tell me I can register this and use it. I would hate to think I purchased this and am not thanksable to use this software. I went through the registration process but it’s very confusing and does not work. Help?