Do i need a memory card for DDR on PS2?

Question

im buying a PS2 with a DDR. I heard I need a memory card or disk. Does it include in the PS2 when I buy it? Or does it include in DDR? or do I have to buy it seperatly?
What's the memory card for/why do I need it?

Answer 1

you need the memory card to save your game, as you need to play the game in order to unlock all the songs
it does not come with the ps2 or with ddr, you must buy is separately
they're usually like $20