Microsoft's Windows Anytime Upgrade (WAU) program (in English) allows you to upgrade the Windows 7 operating system on your computer to another edition of Windows 7. This requires purchase of a product upgrade key from Microsoft.
If you upgrade, Microsoft supports the new version of the Windows software under its terms. HP continues to support the hardware under the terms of the warranty period.
HP or Compaq System Recovery restores the original version of Windows that came with the computer. Your recovered computer will no longer have the upgraded version of Windows.
If you have questions about Microsoft's Anytime Upgrade program including questions installation problems, see Microsoft Help and Support (in English).