Are you looking forward to getting windows 8.1 update for free, but for unknown reasons, you do not have the option to upgrade in microsoft store?
Here is another quick manual way to upgrade to windows 8.1
Here the quick guide to perform the update from windows 8 to windows 8.1
Open up your internet browser. Using either chrome or internet explorer works well.
Type in “ms-windows-store:WindowsUpgrade” into the address bar, press enter and u will force the update to appear.
Remember to backup your data before performing the upgrade to 8.1