In München, when I got one back in 1984 (it is still licensed) you had to get up early in the morning and get in the queue at the "Rathaus". I assume your sister speaks German, so she can make a couple of telephone calls to the "Stadtverwaltung" for you to find out. In most German towns you do not require a licence. I used to love playing in Passau and Nürnberg, which in addition to being lovely cities, are only a morning's train ride from München. The uniformed cops are unlikely to bother you much, even if you are in breach of local byelaws. As long as you are polite and upfront with them, they won't give you much trouble. I have had policeman remove drunks from my show, request encores, compliment me, throw money and even tell the crowd off for being too thrifty. That won't all happen to you on the same day, but you do not need to go out worried about them. If anybody who is not in uniform comes to ask questions, ask them politely but firmly to show their ID. Some towns I have enjoyed playing in the South are Regensburg, Ingolstadt, Passau, Nürnberg, Freiberg and Würzburg. In the North I like Aachen (only evenings), Köln, Dortmund, Essen and almost anywhere in the Ruhrgebiet. If you promise on your Granny's virtue not to reveal them to anyone else, I'll let you know about a couple of my secret small towns near here. However, I'm buggered if I'm posting them on an open forum!