When you purchase multiple license for a product, you will get only one license key. But the number of activation allowed for that license key is incremented (in our license database server) to reflect the number of licenses purchased.
For example, if you had purchased 5 seats, you will get one license key but the key is programmed to work for registration/activation on 5 different users/systems. In our backend, your license key is tagged/allowed for 1 X 5 times activation.
So go ahead and use that license key on multiple users/systems as per the intended number.