No use is required for filing or registering a mark as a German trademark. There is a grace period of 5 years in which the registered trademark owner cannot be challenged for non-use. After the 5-years grace period has passed, the trademark owner may be challenged in an invalidation proceeding for the non-use of his/her trademark. The trademark owner wins such an invalidation proceeding if he/she has started using the trademark for the respective goods/services before the 5-years grace period has ended.