I understand what your saying and ive only put forward the idea of cell memory as a theory because it fits very well with how calluses are formed. Saliva though isnt the only way the skin on the nside of the mouth is damaged - there are many other ways. Licking or eating is enough to make the skin on the inside gradually wear away if you have dead skin there. Saliva just seems to 'digest' the dead skin and make it very weak and so making it easier to peel.
I accept that my theory might not apply to everyone as we all have different sypmtoms. I for one do not get the burning or inflammation only the dead skin that keeps rebuilding. If the condition is caused by something other than lip biting or after lip biting was subject to infection then my theory probably doesnt apply so much.
Having said that it could be that it is simply a case for people with an infection and hyperkeratosis that they have 2 issues to deal with instead of 1. I still think lemons the best way forward though - ive read many accounts of its ability to kill fungus and restore abnormal skin. If there is an infection AS WELL AS hyperkeratosis then it is likely that the infection is preventing the skin form returning to normal.
I think it is important for us all to first recognise what exactly is going on with our lips - mine just seem to produce dead skin and im 100% sure theres no infection after consulting a dermatologist. It bears all the characteristics of a callus that is constantly damaged.
Ill see how the lemon works out after 2 weeks. If its successful (and i'm already seeing signs of progress) ill let everyone know. Lemon could also be the way forward for others with an infection too though the treatment may require more care and possibly the addition of anti fungal creams or whatever after applying the lemon.