"As long as" means at the same time. "As long as you're going to the store, could you get me some bread?"
"Unless" is used to change the statement negatively, somewhat like "if"(which can be positive or negative). "Unless the store doesn't have sourdough, then I don't want any."
It is my kind opinion that your explanation about "as long as" might not be close to the original meaning.Probably, the experts of this forum might add further thoughts on this.
I think how Vorpar used 'as long as' is fine...it means Condition A (get bread) can/will be in effect provided that Condition B (going to store) is met. Ex: This scholarship in the amount of $5000 will be renewable every year as long as you maintain a 3.5 cumulative GPA.
'Unless' can be used in a similar sentence structure, but in an opposite-meaning way. Ex: This scholarship in the amo
You will pass the exam as long as you study hard. = You will pass the exam if you study hard. = You won't pass the exam if you don't study hard. = You won't pass the exam unless you study hard.