Is EB1A green card conditional?

Dear all,
How many years does it give? Do I have to remove any conditions in order to maintain it?

to Phillip:

I don't know the specifics but there are certain requirements with any GC. Like you have to stay in the US for a certain amount of time each year. And if you mess up, your GC can get challenged/cancelled. Have you looked at USCIS website?