I bought a Win7 Home disk 2 years old & install on my PC. Last year it was upgraded to Win10 Home. Last week my friend's old laptop hard disk died & I put in a new one & installed using my Win7 Home disk but when I tried to activate using the laptop's product key, it won't activate. Then I use the product key for my disk as a last resort & it can be activated. That means the product key for my Win7 can be recycled after upgrading to Win10. Anyone with similar experience?