You can transfer that license by registering the soft eLicenser that has your Cubase AI license to your MySteinberg account. Then just follow the steps under “How can I request a new activation code resp. what is the procedure for a reactivation?”:
About the ISO I don’t know, but you could upgrade your Cubase AI 6 license to Cubase Elements 8 for € 49.99. That will permanently add a Cubase Elements download link to your MySteinberg account, and of course it’s also a bit less limited than the AI/LE versions.