Running Factory Recovery from its partition or disks will auto-activate with the factory SLP mass-activation key embedded in the Recovery partition or disks.
This is not the same as the key on the COA sticker which you would manually input if you clean reinstall with a Windows 7 installation DVD:
Which method you choose depends upon whether you want the preinstalled factory bloatware which came with the laptop, or want only the OS in a more lean install which is described here:
Reinstalling Windows 7
Do you understand the difference? Feel free to ask back if not.
If you post your System specs as requested we could link you to the steps for running Recovery.