Every person using or otherwise consuming in this City tangible personal property purchased from a retailer is liable for the tax; provided, however, no tax shall be due hereunder if the tax imposed by Section 21.199 of this Code has been paid on the sale of such property. The person’s liability is not extinguished until the tax has been paid to this City, except that a receipt from a retailer, authorized pursuant to Section 21.5.07 given to the purchaser pursuant to Section 21.5.09 hereof, is sufficient to relieve the purchaser from further liability for the tax to which the receipt refers.