Managed to install 6.1, but although the exe was for WinToUSB Professional 6 it appears to install the free version and there is no activate option
Yes, you’re right, there no difference between that version and the free one.
I have “unpacked” the exe with Universal extractor, and I found the 32 and 64 bit softwares in the extracted folder. Both are free versions and no difference with the installed one which is supposed to the licenced software.