You have to keep track of what save file you're using. But yes, it'll be there when the player restarts the game.
However, in most cases, you want to write to a buffer and then transfer the buffer over to SRAM when saving the game. SMW does this in order to save level progress at castles instead of saving it immediately.
EDIT: For your purposes I recommend using my SRAM patch, which can be found here
. It actually saves you 141 bytes of RAM at $1F49, so you don't need to use anything outside the range of absolute addressing.