(Please note that the steps mentioned here to stop sharing is for Office 365 Home subscription only.)
Office 365 is the latest version of the popular productivity suite that can be purchased to be installed on multiple PCs. In other words, you have to pay only for a single subscription that can be shared among other users. So, if you are the owner of an Office setup 365 Home subscription and you have shared it with others then you are also free to stop it anytime.