[NiteWave]

serial.no no change. no need re-install. as stated in the wiki:

Your license will be updated from our license server automatically once invoice is paid. Your local license key will be auto-updated within one day. If you want it to become effective immediately, Please run following commands to retrieve a new license key,

/usr/local/lsws/bin/lshttpd -r
/usr/local/lsws/bin/lswsctrl restart
assuming LSWS is installed to /usr/local/lsws.

this is all you need do when upgrade/downgrade. it's convenient.