Lightroom can be used standalone, but note: the stand-alone version is the same software as comes from the cloud, so no more or less "safe" - what is your worry?
Adobe has before showed us, that the websolutions is unsafe.
I will never trust any websolution, and I cant see why I shall pay every month, after buying the product..
the stand-alone version is the same software as comes from the cloud - you can verify the MD5/SHA checksums if you don't believe me.
it may be worth elaborating what it is you are concerned about (I'm not familiar with the safety issue that Adobe has "shown us before").
But regardless, Lightroom is available "stand-alone" and will be "indefinitely" so no reason to fret, yet..