@Leo > Back at rekordbox v2, a license was required as at that time, the base version of rekordbox was a paid product. As of v3, it was made available for free. rekordbox 4 continues to be free to operate in a similar manner to all prior versions (to organize music, edit hot cues, memory points, beat grids, tags, link to players, etc.), however with the addition of the performance mode (known as "rekordbox dj"), this is a paid add-on for allowing DJs to use the software to perform directly within the software. This does require a rekordbox dj license, not the old rekordbox 2 license. Unfortunately your license is not valid for rekordbox dj, and in order to use the performance mode, you must purchase either a full license or a monthly subscription. Without this, you can still continue to use rekordbox in export mode for free to do the same things you were doing with previous rekordbox versions.