Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry that you have been waiting for a response, but your requested expert isn't online which delayed your question coming up on the list for all to answer. I would like to help if you are still interested in an opinion.
Thank you for the pictures. It is difficult to see if this is entirely on the outside of his lip or if it originated in his mouth and has now gotten larger enough that it is protruding out of his mouth. What I can see is a firm looking pink mass hanging down from his upper lip.
The short answer to your question is yes he needs to see his veterinarian and have this addressed as soon as possible.
Possible causes of this swelling can be as benign as a foreign body (plant awn or splinter) buried in his lip that has created a lot of inflammation, granulation tissue and discomfort to more worrisome aggressive tumors like an amelanotic melanoma or squamous cell carcinoma.
Your veterinarian will likely want to aspirate the mass, look for local lymph node enlargement and aspirate his lymph nodes to look for signs of tumor or infection spread and possibly take some radiographs of his jaw and chest/lungs to look for possible tumor spread.
This is a fairly large mass given its location and should be dealt with promptly.
My apologies on your wait for a response, please let me know if you have any further questions.