It an be either.
The term is hyphenated as "long-lasting" (persistent, perennial, long-lived).
Yes it should be hyphenated.
Yes, because you're using the phrase as an adjective (example: "This long-lasting lipstick is great."). Definitely use a hyphen.
No, "year long" is not hyphenated when used as an adverbial phrase, such as "The project will last year long." However, when used as a compound adjective before a noun, it should be hyphenated, as in "a year-long project."
It should be hyphenated when it's used as an adjective.
Long-lasting
Yes, "long-term" should be hyphenated when used as an adjective before a noun, such as "long-term goals." However, when used as a noun or after a verb, it is typically not hyphenated, as in "the plan is for the long term." Always consider the context to determine the correct usage.
Some examples of hyphenated words that start with "l" are: long-term, low-key, light-hearted, and life-threatening.
I think Remy hair is the longest lasting hair!
long-legged
Plastic is a non-biodegradable substance. Yes, it is long lasting.
It is not hyphenated.