The license/certification would be from denomination, because Congress is forbidden to pass any law restricting the exercise of religion, and states don't either. The Military requires endorsement from a denominational body. This is not the same as a license. It is usually in the form of a letter, saying you are an accepted clergy person within the body. The usual course for someone to become a pastor is: membership in a church within the denomination, education at a Batchelors level, and seminary resulting in a Masters within a range of schools accepted by the denomination. Then there is ordination, and finally licensure, within the denomination. There are exceptions to each of these requirements in some denominations.
This will depend with the specific rules of your state of residence. Some areas will require you to have these certifications, which you can obtain by enrolling to a Christian ordination program. Here you will undergo some necessary training for this certification.