Do gun owners need to get a permit/license for every gun, rifle, musket they own or does ONE license/permit cover all forever after?

Here we do not need licenses for shot guns.

It depends on the country or state you live in.

In the USA licenses and permits vary from state to state but some other countries issue licenses and permits at the national level while other countries just don't allow it at all.

I live in South Dakota so the laws are:

An individual who wishes to carry a concealed pistol on or about his person or in a vehicle must obtain a Permit to Carry a Concealed Pistol.

A person does not need a permit to own a pistol, keep it in his home, business, or property, or visibly carry it. 

Licenses are for people, not guns.  IF you have a concealed carry license, you may carry any legal weapon in a concealed manner.  Where gun registration is required, that is per gun.

I always here Americans saying "we all know most crimes are committed by illegal guns." If a lot of states don't have licenses for legal gun owners, how do they know if the guns are legal or not? Here in Britain, I believe you need a licence for each gun held. It is up to the Chief Constable to determine if you are a fit person to own a gun, and the tests you have to go through are very strict. Despite this the number of gun licences issued goes up year on year.
https://www.gov.uk/government/publications/firearm-and-shotgun-certificates-in-england-and-wales-financial-year-ending-march-2015/firearm-and-shotgun-certificates-in-england-and-wales-financial-year-ending-march-2015