The KDE logo can be used freely as long as it is not used to refer to products other than KDE itself. There is no formal procedure to use it.
Copying of the KDE Logo is subject to the LGPL copyright
license. Trading and branding with the KDE Logo is subject to our
trademark licence. For more details on their usage please see the KDE CIG
These logos are available for archival and historic reasons, and should not be
used in the creation of new KDE-related content.