Migrating licenses

Hi there,

I'm planning to buy a couple of licenses for me and my colleagues so we test a basic enterprise features before moving into a more advanced and centralised AD infra-structure. Would be possible to assimilate the costs of these licenses we are planning to buy now into a more expensive license and use them as part of the payment? What I don't want end up is with buying licenses that eventually we won't have any use because we decided to upgrade.

Regards,

Alex