Hello!
Yes, you can upgrade (maybe) but first make sure that your PC meets all the Windows 10 requirements:
Windows 10 system requirements - support.microsoft.com
If your PC doesn't meet all the requirements, do not upgrade.
Step 2: Get your license (Note: Windows Vista license may be used with Windows 10. I have upgraded a PC from Vista to 10 and it got activated, but all the PCs aren't same)
- Press Windows+R and type cmd. Press Ctrl+Shift+Enter and click on yes.
- In the black window, type wmic path softwarelicensingservice get oa3xoriginalproductkey and press Enter.
- This will show you the product key. Write it down somewhere. (Note: Do not share it with anyone)
- Then, download and run this tool: Download tool now (microsoft.com)
- Run it and choose Upgrade this PC now. (Make sure you backup all your data).
If your PC doesn't meet the requirements or if you face any problem while upgrading, stop the upgrade immediately.