Lightroom v6 was the last version, introduced in 2015, that Adobe allowed you to purchase (no longer available for purchase) and use forever without ongoing fees - albeit without any updates making it potentially incompatible with your new camera's RAW file and eventually it will become incompatible with your operating system and become redundant
Lightroom CC is the current version with a dumbed down re-designed user interface, which is continually updated but to use it you must pay an ongoing monthly subscription fee, as a result many people are switching to other image editing software
Lightroom Classic CC is the current subscription only version with the old user interface of LR 6 but newer features
if you decide to cancel your Adobe CC subscription, it seems you only get to open it ONCE more so be ready to have exported whatever you need before you cancel - you don't want to lose all those many hours of editing!
to gain access back you need to re-subscribe - this is why I hate subscription models!
Benefits of Lightroom Classic CC over v6
launches faster (v6 is extremely slow to launch)
generates previews faster
imports and exports faster
switches between modules faster
all recent cameras are supported eg. Sonya7III is NOT supported by v6
you will have to use a clunky workaround such as using Adobe DNG Converter to first convert RAW to DNG raw format
Cloud syncing with LR mobile, etc
bundled with Photoshop CC
BUT the CC version will not run on Windows 7 - you need Windows 10 or you need to use LR Classic which is included in the bundle
new features in LR CC:
Creative Profiles
Expanded Tone Curve
Profile Management
Coloured Labeling
Folder Search
Range Masking
Boundary Warp
Haze removal
Textures slider in Develop module - smooth or enhance textures in photos without destroying finer details or adding noise