If you are referring to Get Windows 10 icon, your Win 7 has to be SP1 installed. And all Windows updates need to be up-to-date.
You will need update KB3035583 installed before you will get that icon appears.
Go to your Windows Update > View update history and find out if you have that KB3035583 installed.
However, that Get Windows 10 icon is really NOT necessary.
As long as you have Win 7 with SP1 installed and your copy is genuine , you will be entitled to a free upgrade to Windows 10. And it will be upgraded through Windows Update.
It's just a matter of waiting your turn.