The above messages were written in 2015. I've just tried to purchase an upgrade outright and can only purchase a subscription. Is there another way?? I really dont want to pay $170 per year for the upgrade when I rarely use LR. I just need it to be compatible with my Nikon D750. Frustrating!
LR 6 is in page 2 of the list that above link from 2015 shows. Click the 2 link at the bottom to see the rest of the choices.
Here is what I see if I click to buy LR 6 and choose Upgrade instead of Full and From LR 3.x (in the US):
Also the Photography Plan, which is Photoshop CC + LR CC is $120/year at least in the US, not $170. The LR CC in the photography plan has a few new features that were added to LR after LR 6.0 came out, and feature updates only are available with CC not 6. The Dehaze filter is the main one only CC people get since they're paying a little every month they get the new features as they are released.