I’m considering buying the Nik Collection, but I wonder if there is a portable version available, or ever will be? I usually have all my editing software on external flash storage, so I can be flexible and carry it with me to work any computer that’s available to me.
Knowing a bit about the internals of the software, I doubt that it can work as a portable software.
As the main usage of this collection of tools is through plugins of Adobe software, it has to be installed in some specific locations so that Photoshop or Lightrom detects them. Furthermore the standalone versions, which can be started without a host application, still expect some files to be stored at some places on your computer (and not in the same folder as the .exe files or a relative folder).
This requirement is also true for the license file, which is strongly linked to the system it has been generated for. A working license on a system will not be valid on another system.
The main issue is licensing.
//This requirement is also true for the license file, which is strongly linked to the system it has been generated for. A working license on a system will not be valid on another system.//
Unless any company licences it, portable software would be a breach of licence conditions.
I suspect that creating a portable Nik is possible, as Photoshop, Lightroom and Illustrator (to name but a few apps) all exist and work as portable applications (up to PS 2017 at the last check). They are however against the Adobe Licence and leave you legally exposed for civil damages (in the UK anyway) for using them. These would be even worse if you were using the software in any professional capacity.
(No btw, I will not be telling anyone where to get these version of Adobe software!)
I taught IT up to 2nd year undergraduates including systems / organisational security and portable software was one the issues we covered as it had the potential to circumvent company defences. There are LOTS of portable versions of many types of well known programs around, not just the Adobe ones. Many also contain various nefarious add ons you may not wish to have near your PC too!
//it has to be installed in some specific locations so that Photoshop or Lightroom detects them.// You can point portable software at them and they will be recognised.
However, as Nicolas implies, they would be a pain to try and use as a work tool if you did not know what you were doing. They have the potential to leave your system exposed to threats and run the risk of fines and damages as well as the software suddenly not working at critical moments.
There are plenty of legal options available and with DxO giving multiple licences with each piece of software I’m not sure why you would want a portable version anyway.