Although it requires no installation as advertised, BN is not natively portable as it saves settings to '%LOCALAPPDATA%\WinTools.Info' as well as 'HKCU\Software\Classes\Black NotePad'. Minimum DotNET requirement is v4.0.
Black NotePad is a plain text editor program. It carries out similar tasks to Microsoft Notepad while significantly supplementing and exceeding its functions. An essential function is the option to easily switch between display modes. [...] Black NotePad doesn't require installation, it supports Windows 7/8/10 operating systems. Black NotePad is fully usable for 30 days after it was first started. After these 30 days, you can activate the software. [...] You can still use the software without activating it, with some minor limitations.
Black Notepad latest release (currently v2.0.0, dated 2020-06-09) can be downloaded from https://www.wintools.info/index.php/download.