It looks purple in the picture. Pictures maybe misleading with lesions. Also, you have not provided any history...as in...any pain or burning with it or for how many days you have it etc. Any lesion that doesn't disappear in 2 weeks should be shown to your dentist or oral medicine specialist.  The earlier the better. Take care

Petroleum jelly application as many times as possible. Followed by CNBC tooth and gum gel application with fresh cotton ear bud 4 times/day. Keep applied for 3 minutes and rinse.

There are few questions to be asked  to diagnose the lesion 1)how long the lesion is present 2)do you have habit of smoking? 3)if smoking isnot there what kind of lip bum/cream you are using 4)is this lesion seasonal or not Etc..