Reactivate HSO on new machine

I used HSO on my previous PC under Cubase Studio 5. I’ve upgrade to Cubase 6.5 on a new Mac. I installed the HSO trial that came with 6.5 expecting it to pick up my existing licence, but it didn’t. I’ve activated the trial so it’s working at the moment, but I assume this will expire at the end of the trial period. How can I get my new HSO installation to recognise the old licence on my Steinberg key? and/or how do I reactivate?