Dynamic Ax provide the option to create purchase order against one-time vendor or supplier. It means one-time vendors can transact only once.
If you create a new purchase order, you find this option at the top of vendor creation form.
There is possibility that we can create multiple one time vendors or supplier against normal supplier. For that we can select vendor in Invoice account.
Dynamics Ax provide a separate sequence number for one-time vendor / supplier. You can set this sequence number form Account payable parameter form.