So apparently no licensing problem in Germany - just the normal regulations about public disorder, noise etc. This bit is interesting though (rough translation)

"The singing of certain songs - irrespective of the number of persons taking part - may fall foul of the criminal law, for example because the lyrics have an insulting or derogatory content, or would incite to hatred or violence."

Is there a list of banned songs in Germany, or do they just act on an 'ad hoc' basis?