May be a chicken and egg situation. Is he licking because his lip is sore or is his lip sore because he is licking. There are several conditions that affect the older cat some of which are potentially serious so it would be handy to know how old he is and if he has been neutered.
In general the first thing to check is his mouth for signs of gingivitis tartar bad teeth or breath. Any sdign of any of these get him to a vet. To stop him licking objects make an Elizabethan collar that projects well forward of his nose from something like a youghurt pot or rubber plant pot with the bottom cut out and fastened to a collar. Keep him in when this is on and remember to take it off for him to eat and drink. Give the sore area 1 good bathe with strong salt and water solution (1 heaped tablespoonful of salt to a pint of boiled water) dry it well with tissue and gently hair drying if the cat will tolerate it. Apply thin smear of vaseline and see what it looks like after 24 hours. If it doesn't look any better then take to vet if it does continue the same.
I am available all day on 1 call advice direct vet 0906 11 11 999 if you want to discuss this in more detail.

15/1/06

Thanks. Try the advice as originally suggested. I am interested to hear how it goes on.

15/1/06