Selling spare licence

Hi,
I bought Cross DJ 1.6 in October 2011.
I then bought Cross DJ 1.7 in June 2012.
I didn't realise that if I had properly registered my 1.6 serial number on here then I could have downloaded 1.7 etc without paying again. I realised afterwards. I am currently using 2.5 and registered here via the serial number bought for 1.7.
My 1.6 serial number is therefore "spare". Am I allowed to sell it or give it away? If so, will the other person be able to easily register here and gain access to the proper download link for the current version?
Thanks
I bought Cross DJ 1.6 in October 2011.
I then bought Cross DJ 1.7 in June 2012.
I didn't realise that if I had properly registered my 1.6 serial number on here then I could have downloaded 1.7 etc without paying again. I realised afterwards. I am currently using 2.5 and registered here via the serial number bought for 1.7.
My 1.6 serial number is therefore "spare". Am I allowed to sell it or give it away? If so, will the other person be able to easily register here and gain access to the proper download link for the current version?
Thanks