Your subscription is not tied to one device, but you can only stream on one device at a time.
For example, you can use your subscription on your tablet, smartphone, Android box, Smart TV, etc. as long as only one device is active at a time.
This allows you to keep streaming on your phone as you move around your house, or switch from the TV in the living room to your laptop in your bedroom.
Just make sure you close the stream on one device before opening it on another one!