Most Unifying devices can connect with Unifying receivers an unlimited number of times. Some Unifying devices have a limit of forty-five (45) unique connections. If you're using such a device with multiple receivers, once you connect 45 times, you won't be able to connect to additional Unifying receivers. The device will continue to work with the last receiver it was connected to.
You can power your device off and on an unlimited number of times. The mouse doesn't go through a connection process when powered on, so this will not count toward the connection limit.
If you have to reconnect your mouse to the same receiver for any reason, your device will recognize that the receiver itself hasn't changed. This won't count as a unique connection, so it will not count toward the connection limit.
You sometimes use your mouse with your desktop computer, and other times with your laptop computer, but you use the same Unifying receiver (moving the receiver between your laptop and desktop). Because you only use one Unifying receiver, you will not hit the connection limit.
You have two Unifying receivers: one on your laptop and one on your desktop. You use the same mouse with your laptop and desktop, and switch back and forth between the two Unifying receivers. Because your mouse is switching between two Unifying receivers, each time you connect, you use one of the total available connections. Eventually, you will hit the connection limit.
If you're unable to connect your device to another Unifying receiver, please contact Customer Care.