usually if you check to remember a network, it adds the keychain entry to your user keychain AND the system keychain, so all other users of that computer will also have access to the wireless. (but they cannot recover the password since it's in the system keychain)
If you are having problems, I suggest removing the keychain entry from all keychains, including theirs, yours, and system, and reboot and try again. It should prompt for it, click to remember, and it should work for all.
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