How many times can I upgrade to Windows 10?

[Windows Central Question]

windows 10 upgrade

I upgraded my windows 8.1 to windows 10 and installed nvidia graphic driver which was windows 8.1 supported and restarted my pc. It had shown a black screen with blinking cursor. So with HP recovery manger I recovered my PC with windows 8.1. Now again I got an update to windows 10. Can I update once again to windows 10..