I want to upgrade from LR5 to LR6. Purchased a full version of the LR6.
What happens if I use this?
What happens? Everything should work fine.
Can you be a little more specific about your question?
Will this work as a regular upgrade or will LR6 add themselves as a separate program?
LR6 is a separate program. You can, if you want, upgrade your LR5 catalog file to LR6 (I recommend doing this).