The Missouri definition of “sale at retail” has been expanded to include software load and leave transactions since the customer purchasing the software is actually purchasing the right to use the product. A load and leave transaction describes a sale of software, delivered to the purchaser via tangible medium for installation, but then the tangible media is returned to the seller, or taken with the seller or installer, once the final installation is complete. The Missouri Department of Revenue also states that any previous letter rulings or opinions previously issued are “withdrawn and should not be relied upon or considered to be indications of current law or policy.” (Missouri Tax Policy Notice TPN16, Missouri Department of Revenue, January 9, 2004)