Ohio Rev. Code Ann. § 715.62

In the trial of any action brought under section 715.61 of the Revised Code, the fact that any party to such action represented himself as engaged in any business or occupation, for the transaction of which a license is required, or as the keeper, proprietor, or manager of the thing for which a license is required, or that such party exhibits a sign indicating such business or calling, or such proprietorship or management, shall be conclusive evidence of the liability of the party to pay such license fee.