help Final fantasy dissidia duodecim

[Crypt96]

I ran into a problem with the game i recently obtained.

I recently got a copy of Dissidia duodecim for the psp go and the game says it needs a memory stick to save data. Well if you know the PSP go, it has 16 GB system memory (varies with system i heard some have 8gb) and the game will not save data on the system storage. IDK if it is the rom or the system, but do i really need a mem card if the system has 16 gb of storage?

IDK why the game needs an external memory card, but an answer is needed swiftly before i go buy a M2 card that is really only needed for one game on my system. Is this the only game that requires external memory?