When 1st run Abelssoft JetDrive shows a form window -- fill in your name & email & click the button, and Ablessoft will send an email with a special link -- click that link and when the page opens in your browser it says the app is now activated. When you start Jetdrive you get a UAC prompt listing the publisher as Ascora GmbH. The software adds a folder to Program Files [Program Files (x86)], but its primary folder is in ProgramData -- not a huge problem but unusual. You also get a folder in Users\ [UserName]\ AppData\ Local\ along with 6 Segoe fonts. I recorded 114 new registry entries in my Win7 32-bit VM, mostly Windows stuff like cache, with the app itself adding one key for uninstall & the fonts.
JetDrive is a simple defrag app that, unlike Auslogics' Defrag Ultimate for example, doesn't give you a choice of optimizations. The basic idea behind defragging a conventional hard disk is that, because files are stored in small chunks of data that can be spread far & wide, it works better if all the pieces for each file are grouped together, which is what defrag does. With a conventional hard disk, data is stored on circular platters, with tracks towards the center having a smaller circumference than those on the outer rim. That means the stored data is read faster or slower depending on where it's physically stored. In addition to grouping all the parts of a file together, an app like Auslogics Defrag Ultimate will put critical files where they will be read fastest, which can help Windows start faster etc.
Defragging a hard disk crams all the stored data at the beginning of the partition, & so it should be done before shrinking a partition, or as a 1st step in compacting an expanding [variable rather than fixed size] VHD. Though they use Windows to actually optimize the disk, 3rd party defrag apps will usually go further than Windows in packing data at the beginning of the partition, though using Windows own optimization *may* move more Windows system files that those 3rd party apps say are unmovable. So use Windows 1st, then a 3rd party app if you want max results.
The bad effects of running defrag on an SSD are often [usually] overblown when you consider the SSD's rated number of writes over its predicted usable lifetime, but when you also consider defrag's original purpose, defragging an SSD seems senseless. That's not entirely correct. While you don't need to run a 3rd party app's defrag on an SSD, Windows itself needs to defrag SSDs monthly, so don't turn Optimization of SSDs off in Windows.
hanselman[.]com/blog/the-real-and-complete-story-does-windows-defragment-your-ssd