I assume what you have on your lip is a Fever blister and if it is it should start to go away within a few days but can take up to a week to fully heal up and go away.
You can help the Fever Blister on your lip heal faster by applying some antibacterial ointment to the blister.
You can also get rid of the fever blister on your lip by applying some tea tree oil to the fever blister or even some ice to help it go away.
Witch Hazel also works to get rid of fever blisters as well as taking Lysine can make a fever blister go away faster.