I bought CS5 Creative Design Premium Suite and have been using it on Windows. I recently moved to Mac and would like to swap my license to Mac. How can I do this? Thanks!
You can't. You can only do a platform switch with current versions.
You have two choices. Upgrade to CS6 or move to Creative Cloud.
In either event you must do so directly through Adobe and FWIW, my advice is to go to Creative Cloud.
At $29.99/month for the first year it's a steal.
What Bob said. Read the details here: Order an Adobe product platform swap or language swap