Both are correct. Which form you use depends on its context within the sentence. Where the phrase denotes an adjective, then "longtime" and "long-time" are correct. Otherwise the phrase is split and "long time" is the more appropriate form. See the following examples.
"A long time ago in a galaxy far away."
"Our family hasn't had sushi for a long time."
"Grady greeting his longtime friend at the airport."
"Stacy is a longtime fan of the Jets football team. GO JETS! <3 (:"
Maybe the following sentence will help . . .
"It has been a long time since I have seen my longtime friend, Tom."
The word can be spelt as a single word or hyphenated, though it is probably easier to spell it as one word so that it doesn't get confused with usage in a phrase such as "a long time ago".
life-long
No
One
The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.
No, the correct spelling isopportunities.
Tomorrow is the correct spelling.
The correct spelling ispreferably.
The correct spelling is 'adjourned'.
The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.The correct spelling is privileges.
No, "VAXINATE" is not a correct spelling. The correct spelling is "VACCINATE."
No, the correct spelling isopportunities.
Tomorrow is the correct spelling.
The correct spelling is "opened".
The correct spelling isproctopexy.
The spelling employees is correct.
That is the correct spelling of the word "imagination".
The correct spelling ispreferably.
The correct spelling is someone.
The correct spelling is measurable and not measureable.
The correct spelling is stayed.