The PSP Go had 16 GB of internal flash storage. This built-in memory was central to the model’s design because Sony removed the UMD drive used by earlier PlayStation Portable systems.
The PSP Go, model PSP-N1000, was released in 2009 with a sliding screen that concealed its controls. Instead of buying or carrying UMD discs, owners downloaded games and other media through the PlayStation Store and stored them in the console’s internal flash memory. The system also accepted Memory Stick Micro, or M2, cards for additional capacity.
The 16 GB figure describes the internal storage, not the PSP Go’s RAM and not the maximum capacity of an expansion card. An M2 card could extend storage by up to 32 GB according to the model’s documented specifications. That distinction is why answers such as 32 GB or 64 GB do not fit the question.
The digital-only approach made the PSP Go smaller and lighter, but it also meant that physical UMD game discs could not be inserted or played directly.