You can look at your state's Financial Department's website and they should have a licensee database . . . .
Payday loan companies can't garnish your wages without a court order. But they can and do put clauses into the contract saying that you give them permission to "assign" your wages in the event of a default. This is completly voluntary. All you have to do to prevent this from happening is send them a letter certified mail that says "I revoke any and all wage assignments I may have signed with XX company." Keep a copy in case you need proof that the wage assignment was revoked.