The free upgrade to Windows 10 is still available, if your PC is compatible with the system requirements.
To upgrade, download Media Creation Tool from the official Microsoft's page and run it. Next, choose Upgrade this PC now if you are running the tool on your Windows 7 PC.
Your PC will be upgraded to Windows 10 without having to enter a product key. If asked, enter your Windows 7 product key. Once the upgrade completed, you can check the activation status of Windows 10 by going to Settings > Update & Security > Activation.
Only Windows 7 Professional and Ultimate will be upgraded to Windows 10 Pro. The other versions, including, Home Basic, Home Premium and Starter, will be upgraded to Windows 10 Home.