How to change Locale from en_US to de_DE

I am using CC and had to find out that I am only able to us the en_US locale.

I was using Photoshop and Lightroom full versions before and could choose the language.

Now it is limited to jus _one_ locale. I tried to load the de_DE local from the previous version and got a license error: only one locale allowed with this license - or similar message...

I would like to use de_DE

Any idea?

Thanks

Matthias