You would have to contact Keil direct for it.

However, I think they might disagree that you "have a correct an full license for the package" - since the Add-On Disk forms an integral part of the licensed distribution!
If the crowd you bought this from didn't give you the Add-On Disk, then they are probably in breach of their licence terms, as they did not give you the complete package!

Anyway, you need to talk direct to Keil - it's a legal licensing issue between them & you.