I bought 6.47 back in Sept 2020. When I installed it and saw that it was too dark to read I asked NCH if there was an alternative light interface and they said No, so I got a refund.
(I have at least 4 other licences from versions 1 & 2, but some were buggy and fixes didn't work, others won't work on Windows10 any more, so now I only have one that's functional and I need another. It pains me to lash out on payware that expires, but needs must.)