I have owned Lightroom 6.0 for many years and recently logged into Creative Cloud Desktop for unrelated purposes. The CC app actually showed that it recognized my two licensed and installed Adobe desktop apps (per the attached image), but if I am logged into Creative Cloud Desktop before starting Lightroom, then the latter will show its splash screen, its main window will begin to initialize and then it will exit without a warning.
I can login to Creative Cloud Desktop after Lightroom has been running and not experience any obvious conflicts. Also, simply running the Creative Cloud Desktop app does not trigger this issue: I must be logged in for Lightroom to have a problem starting up.
It's not currently a big deal for me because I am able to work around this, but seems like a bug unless there is something unique in my Windows 10 environment which might somehow help cause this condition to trigger. So, I'm curious if this is a known issue, because I wasn't able to find prior reports through searching.
It was not at all obvious that my perpetual license Lightroom 6 would suddenly be considered in "Subscription" mode simply because I logged into the Creative Cloud Desktop app in Windows.
Some months ago I needed to reinstall my Adobe apps - all of which are perpetual license (i.e., Lightroom 6, After Effects CS6, Photoshop CS6) - and when checking in my Adobe account it told me that I had a "Free membership" to Creative Cloud, leading me to install the Creative Cloud Desktop app:
I suppose that ad was a bit misleading, because it never implied that my re-installed Lightroom 6 (perpetual) would then be enforced as the subscription version.
Curiously, the Creative Cloud app does not seem to affect my ability to run After Effects CS6 or Photoshop CS6, only Lightroom 6.
Since I'm not interested in upgrading to the Adobe Cloud, I guess that means I can uninstall the Creative Cloud Desktop app at this time, with no ill effects and no lost benefits.
TBMK Lightroom v6 was the one App, and only one, that coud be installed as 'Perpetual' or 'Subscription' modes, whereas the Creative Suite Apps only required Activation (without the CC Dsktop App). It was with the upgrade to v7 (aka Lightroom-Classic v7) did Lightroom go fully subscription only.
A 'Free' Adobe Creative Cloud membership is available to anybody that can allow anybody to use the [Free] Adobe Bridge App, but it does 'lock you in' to then subscribing to other Apps- all licensed by Adobe under the Creative Cloud.
I cannot think of any other Photography app 'parcels' that are better value than the Photography Plan (20GB).