WM Keeper, besides prompting for your WMID and password, will ask you to show where the secret keys file is located and to enter the code to access it.

Your secret keys saved to a file (along with the access code) are like your passport. You don’t have to show it every time you do something but you better have it handy if you have to prove your identity.

On the other hand, you should take precautions to make sure noone can steal your keys and access code. Store it on secure media (like CD or flash memory card). You could even make a few copies on several removable storage devices.

Make sure you don’t forget or lose the access code or your file with secret keys will be useless. The access code is created on your computer and is not registered on our servers. This means, if you lose it, we won’t be able to help you restore it. We simply will not know it

See also: 

What do I do if I lost the file with WM Keeper secret keys?.