It could be a number of things, but I will need some more information. What breed? How old is he? How often is he bathed/groomed? What food are you using?
What do you mop/clean with? Carpet powder? pesticides in yard?
As a groomer I see this a ton! Sometimes it starts out as a topical irritant and then becomes a behavorial issue.
It could be caused by food, but then you would be having ear problems and other skin issues, too. Thinning coat, scratching...
Usually grass and dust allergies run about the same.
If you think it is allergies then putting raw local honey in his food is a must. Also, probiotics, omegas (fish oils) and a digestive aid like papaya. Some dog foods are marketed with allergies in mind so just pick one with out grains like corn and glueten.
Until I know more, get a bottle of bitter apple and spray those paws to stop the licking.
the one that is licking he's feet is carson my labrador weimaerner mix he is around 3, he gets a bath every month and brushed once a day we don,t use a mop in the areas he is allowed in, no pestisides ever get in my house no carpet powder, no thinning coat, he is no perfect health other then the fact that he is a tad over weight probly about 10 pounds
another thing about the foot licking thing is he only does it at night.