This is a written agreement between all parties involved in the business and will need to be notarized and filed with the Clerk of the Circuit Court. There is no special form to use or file. You may want to check with the library for books on how to write this agreement or go to the Clerk's Office to view agreements already registered.
Once the business is classified as a partnership, a tax return for a partnership will be filed at the end of the year. If each party decides to file a Schedule C (Profit or Loss from Business) to report money earned, each is responsible for their own license. Filing a Schedule C is for a sole proprietor, not a partnership. Please consult with a income tax professional.