Windows 7 is set to reach End Of Life (EOL) on the 14th January 2020. The mainstream support ended in 2015 with the extended support running until 14/01/2020. Windows 7 was released in late 2009 so has done a ten-year stint, not bad.
After this end date Microsoft will not be supplying security updates or technical assistance and they strongly suggest to anyone still using Windows 7 to upgrade.
The free upgrade to Windows 10 ended in 2016. To get Windows 10 you need to purchase a copy and upgrade your current system if the system meets the requirements of the Operating System (OS). Older Windows 7 devices may be able to run the software but the extra strain on the resources will cause the system run at a reduced experience.
If you continue to run windows 7 your PC will still work but will be unsecure and will become incompatible with other software that has continued development.