The Windows 8.1 support period will end on January 10, 2023 which means it is time to upgrade to Windows 10 as soon as possible.
The upgrade from Windows 8.1 to Windows 10 is quite simple, free and can be performed without loosing any data.
Backup your data
It is always recommended to backup your data on an external hard drive in case something happens to your computer. This means it is now a great time to create a backup (if you don't already have one).
Download the "Windows 10 Update Assistant"
Open this page https://www.microsoft.com/de-de/software-download/windows10 and click on the "Update Now" button. Then execute the downloaded programm.
If there is no "Update Now" button visible on the page, you can simply download it with this direct link: https://go.microsoft.com/fwlink/?LinkID=799445
Perform the upgrade
After the assistens has started just follow the steps in the wizard. Accept the license terms, choose the option to "Upgrade this PC now" and in the next step "Keep personal files and apps".
Then the assistent will download all required files (around 4-5 GB) and performs the installation.