Licensing
Most of the licensing information you require is described in detail in the Autodesk publications Installation for individuals, and Installation for administrators.
This supplement tells you about the license and tier you need for various analyses.
Autodesk Flex
Autodesk Flex is a pay-as-you-go option. If you don't have a subscription to Moldflow software, as long as you have an Autodesk Account you can buy and use Tokens for occasional access. See the Flex Rate Sheet for the estimated cost per day.