Software provider will give you official copy of their casino software to do business with which is like those Curacao is doing whereas to operate the casino business, you must get approval from governments to provide gambling services to a country which is again being termed "license" but for different things.
Basically if you develop your own software then you need only one license which is regulatory approval from a government to provide gambling services to their people. Software license is easily available by paying the fee whereas government license needs lots of documentation and regulatory terms to be followed to make sure that a casino will not be breaching the laws of that country.