Cross / Cross DJ licensing query

Hi,
I bought the U-Mix Control Pro 2 which came with Cross DJ, which is now installed on my laptop. I have recently upgraded my MIDI controller so the U-Mix Control Pro 2 is surplus to requirements. I want to sell it but keep my access to the software. Will I and the new owner both be able to use it?
If not (please explain what prevents this from happening), if I bought the upgrade pack to Cross (DVS version), will I get a new license key, meaning I wouldn't need the old Cross DJ license key anyway?
Kind regards
I bought the U-Mix Control Pro 2 which came with Cross DJ, which is now installed on my laptop. I have recently upgraded my MIDI controller so the U-Mix Control Pro 2 is surplus to requirements. I want to sell it but keep my access to the software. Will I and the new owner both be able to use it?
If not (please explain what prevents this from happening), if I bought the upgrade pack to Cross (DVS version), will I get a new license key, meaning I wouldn't need the old Cross DJ license key anyway?
Kind regards