Rekordbox 6 or 7 with used DDJ-200 / Hardware unlock does not work

Hello,

I bought a used DDJ-200 and read that no key or subscription is needed to run Rekordbox 6 or 7 with it as its hardware will unlock the software to performance mode automatically. Unfortunately its not working for me. Rekordbox 7 stays on free plan only while the DDJ-200 is correctly identified by the software.

How can I get this hardware unlocking feature work? Is it maybe because of the USB cable being not the original one or due to the used status which might have it still attached to another account?

Or do I simply misinterprete the "Free" sign in Rekordbox 7? 

Any help would be really useful.

Lars