HDR projects 4 Pro has been given away before, and it's not bad, although it's much more tailored to special FX than HDR. Photoshop & Lightroom do HDR itself better, as you'd expect, and make a sort of specialty of HDR panoramas, but you also might look for Aurora, which has seen older versions given away.
Your eyes work better than any camera -- you can see in a room that has lots of light streaming through a window, and still see through the window. A camera cannot -- it can only capture a limited amount of dynamic range, light to dark, white to black. HDR is simply taking one photo at an exposure setting appropriate for the window, and a 2nd with the exposure tailored for the room, and then combining the two. Photoshop/Lightroom let you save the combined photos as a [Very large] .dng file, an Adobe RAW format, which is a bit unique among HDR capable software.
That said, higher end phone cameras are as much, if not more about the software than the optics & sensor, and some can do arguably nice HDR without the hassle of taking 2 or more shots. Better standalone cameras let you bracket shots -- automatically take more than one photo, e.g. one lighter, one darker, and one in the middle -- while cheaper cameras may let you set & lock the exposure with the camera pointed at one place, letting you then point the camera somewhere else for the shot. You could lock the exposure for the more dimly lit room for example, then take the picture pointing the camera at the window, and then a 2nd normal shot, still pointing at the window. Or if you don't want to bother with all the HDR fuss, just take 2 [or more] photos and copy/paste parts of one into the other as needed.
If you like HDR projects, emails from Franzis will sooner or later feature a decent price on newer versions. Franzis software is generally light weight... You can most always copy the installed program's folder to another PC, laptop, &/or copy of Windows, run the app, and then register/activate it as necessary. Plug-ins are handled differently depending on the app & it's version. I've seen them included in separate folders once you unzip the file to get the setup app, and I've had to use Universal Extractor on the Franzis setup file to get them. Especially with the giveaways, I've found the Franzis setup routine does a poor job of installing those plug-ins where they need to go for your image editing apps. Usually I've found the plug-ins work well copied into the program's folder, copy pasting either shortcuts to the plug-ins, or the plug-ins themselves into those folders. Bear in mind however that many Franzis plug-ins have limited functionality -- while some will work as FX, many others only work to export your work into the Franzis app.