1. Download here and install Perfect Keylogger 1.6.8 to your own computer first then try using it on yourself to get a feel of its features.
2. Go to the installation folder and copy the 3 most important files bpk.exe, bpkhk.dll and bpkvw.exe to your flash drive (you may uninstall it now from your own pc).
3. Go to your target's computer and paste the said 3 files in any discrete directory to lessen suspicion then configure to your own needs.
4. After the target computer have been used, get back to it some time and use the viewer to see the logs of all keystrokes it collected specially passwords.
Countermeasures : None that i know of if registered version is used..
Additional Notes :
1. If you want the program to be highly undetectable by antiviruses and want its full stealth features, purchase the latest version from blazingtools.com
or look for its registration code floating somewhere on the internet. Be careful though of getting malwares or spywares instead.