What license and regulation means basically is that if you find out a casino is cheating you of your money, you can complain to the registrar to take action against them. For example, a Bitcoin casino licensed and regulated under the UK Gambling Commission is much more trustworthy than a Bitcoin casino licensed under the Curacao eGaming license. Having said that, in order to ensure that the licensing of a specific website is actually worth anything, it’s important to see where it was licensed. Most licensed sites will have a link to their licensing certificate somewhere around the lower part of their home page (i.e., the footer).
This will be another step towards validating the trustworthiness of any casino. Just as you want to make sure the casino is provably fair, you also want to make sure the casino is licensed and regulated. Is the casino licensed and regulated (and by whom)?