Spoofer is a software that make new virtual indentificators for you hardware (mobo, cpu, hdd, etc).
Some spoofer don't make new virtual indentificators, but change the one you hardware have, but this can lead to a lot of problems, so it is nod advised.
There two ways to use spoofer:
Before being HWID banned, where you use the spoofer, cheat, and doest matter if you got banned, because you real HWID still safe.
After you get HWID banned, where you use the spoofer and then login the game to cheat.
About the cheats on MEMORYHACKERS, they now have MATRIX loaded on them, which is the HWID spoofer MEMORYHACKERS provide, so you are safe to cheat with the tools this sites offer, tho you should always check the MATRIX thread to know if the game you are cheat still suported .