However, there is one drawback: AFAIR, Siglents software EasySpectrum will not work without the serial number. If you would like to use the analyzer for doing pre-compliance measurements, the software saves a lot of time and makes things much easier.
However: I cannot test/confirm this, as my unit does have serial number and all options. Maybe somebody can double check this.
But I am pretty sure that EasySpectrum was very sensitive about the connected analyzer.