I have a service animal due to my having Multiple Sclerosis.

first thing you need to know is each USA state has its own standards of what a service animal needs in way of certifications, licensing, training. some require more, some require less and some require none at all. I have found in my travels for work to have all certifications, licensing, training certificates handy. that way no matter what and where my work sends me I am fully prepared.

if you do not plan on doing any traveling to other states then the one you legally reside with in your own treatment providers (medical doctors or other treatment providers you may have) will be able to give you the information that your location needs to qualify your animal as a service animal.

here where I am located the process is that you contact an agency that specializes in service animals, they register you and match you up with the correct service animal for your disability, your life style and what kind of person you are.

or

a person can choose their own type of service animal and then go through the training together with the service animal.

public places and buildings and agencies dealing with the public can not ask you to prove your service animal is an actual service animal except for law enforcement fire, ambulance, medical. .....Unless.... your service animal is not visibly designated. when a service animal where I am located is not visibly designated as a service animal it is appropriate for anyone dealing with the public to ask or require the proof, they do not usually ask but I have encountered situations where other patrons have made a complaint when the location is visibly marked with a no pets sign, or due to allergy to dogs in restaurants, public transportation and other places where dealing with the public happens. therefore I keep my service dogs vest on with all the credentials in the vest pocket. saves a lot of time and trouble.

my best suggestion is go according to what ever your treatment providers have given you for information when they have prescribed \ suggested a service animal for or to you.