When you sign into Windows on a single-user workstation and start one of the Office 365 Pro Plus apps, such as Outlook or Word, for the first time, Office installation on that PC will be automatically activated using one of the five licenses that you are entitled to under the current licensing agreement with Microsoft. This will be recorded in your Microsoft work account profile on portal.office.com (https://portal.office.com/Account/#home). In addition, the copy of Office on that PC will be "branded" with your e-mail address, as in this example:
If other users sign into Windows using their credentials and use one of the Office apps, they will also see your e-mail address under "Belongs to" tag. This is not a bug; it is working the way Microsoft intended. If you inadvertently activated Office 365 copy on someone else's computer and would like to remove your e-mail address from it, you need to remove this activation from the list on your Microsoft work account profile on portal.office.com (see Related Articles for more details).
For multi-user workstations, such as classroom computers, lab computers, etc., Office activation behaves differently because it is deployed in a shared activation mode on those machines. When you use Office on those types of computers, the activation does not count towards your five computers limit, and your e-mail dress will not be displayed under "Belongs to" tag.
