Each new order does require an MTA because it is unique to the items requested and lists specific information pertaining to the recipient, such as the name and address of your institution.
Addgene does not own any of the materials that we distribute, and we have a responsibility to our depositors and any applicable third parties to ensure that these materials are distributed under certain terms and conditions, including the UBMTA and if any, a declaration of third party rights.
The MTA ensures that the Recipient Scientist and recipient organization agree to the terms and conditions of the UBMTA when using the requested materials.