A Blue Sky Surety Bond is a license surety bond required by many states of security dealers. Blue Sky laws are regulations enacted by states to prohibit the sale of worthless securities and to protect the public from fraud. The bond guarantees a purchaser against any loss caused by false representations on behalf of the securities dealer. If you are getting licensed in multiple states then you will need to get a separate blue sky bond for each state license. If your state does not require a surety bond to obtain your license then there is no reason to get one.
The state sets the bond amount and the bonds usually renew annually. You will need to keep the bond in place as long as you keep your license. Annual premium rates (your cost) are often 1-3% of the bond amount. The underwriting requirements may be just a simple one-page application used to soft pull your credit but occasionally additional information may be required.