No, why would you?
If you bought a retail product, you can reinstall as many times as you like, even to different hardware - you just can't have more than one licence active at any one time.
If you got an OEM package, you can still reinstall if your hardware is faulty, and you're replacing a broken part with a new one within the warranty period, you are free to reinstall and activate Windows.
If you have an OEM licence, and no parts are being replaced in-warranty, you can still freely reinstall if your system is inoperable due to virus damage or data corruption.
So whichever case it is, there's no need to spend any money.
