Terraria Global Key?

Is this Key Global so that I can use it in Germany

On Salad, when no detail is given as to the location of an item, it usually is global. Always check the description as well.
If no mention whatsoever is made anywhere, the code will be global (or ROW - Rest Of World).
If a mention is made, then it’ll work in that specific region.

I looked there is no detail so its for every Country or ?

Absolutely, it looks like this item is available everywhere.