Akid is incorrect, the EULA does not allow you to have "three installations running at the same time" on an unlimited number of hardware devices. You must assign a license to a device.
- RETAIL LICENSE TERMS
- OVERVIEW. These license terms permit installation and use of a copy of the software on three devices, along with other rights, all as described below.
- INSTALLATION AND USE RIGHTS. Before you use the software under a license, you must assign that license to a device. That device is a “licensed device.” A hardware partition or blade is considered to be a separate device.
a. Licensed Device. You may install one copy of the software on three licensed devices in your household for use by people who reside there. The software is not licensed for use in any commercial, non-profit, or revenue-generating business activities.
According to the wording, your laptop should count as one "device", regardless of the number of VMs you run on it. If there is an activation issue you can call Microsoft and explain that it is one copy installed a number of times on different VMs, but on the same hardware device.