Your "Friend" has installed a pirated copy of Windows 7 on your laptop. The PID is the Windows 7 OEM:SLP serial for Lenovo Ultimate. Which got Leaked from Lenovo before the company was about to start selling there preinstalled OEM systems
with this serial in use on them. The serial quickly spread over the internet & was included in hackers hacks/cracks, Microsoft then blacklisted the serial with the WAT Update. No OEM systems shipped with this serial in use on them.
You need to use the recovery partition on your laptop to restore the OS to it's previous version which the COA sticker on the bottom of your laptop is licensed for. If this recovery partition was wiped out with the install of Windows 7, you will need to
ring up & order a set of recovery disks from the Manufacturer for your system. (A fee will apply) so you can factory reset your laptop.