Rekordbox v.5.8.7 + CDJ 400 License Key

I bought 2 CDJ400 but I haven't got the License Key necessary to use the Performance Mode on Rekordbox (v.5.8.7) (I don't want to use the new Rekordbox 6 because my CDJs don't work with it).

Is there any solution in order to get back the License Key (maybe via the CDJs serial numbers)?

Are you able to provide me the License Key?

Thank you