Pulse defaults to 80% volume for two very good reasons.
First, the JBL speaker inside each Pulse bulb has a very loud potential output. Different sources of music can have very different levels of volume and the 80% default is a simple safeguard to protect your family’s ears.
Second, the Master bulb emits two "ping" sounds - once when it is powered on and once again when it connects to your smart device; the 80% default volume setting ensures that you hear these two pings.
Currently, Pulse does not save your previous volume settings after disconnecting.