You can use Rekordbox for free to manage your library, set cue points, and prepare tracks for USB export to use on CDJs.
Pioneer DJ changed their model with Version 6, making it much easier to access without a traditional license key:
Most Pioneer DJ controllers (like the DDJ-400, DDJ-FLX4, or DDJ-1000) act as a physical key. Just plug them in, and Rekordbox unlocks "Performance Mode" automatically for free.