Dynamics 365 Finance and Operations are licensed per user or computer on a monthly subscription basis. Monthly subscriptions or annual perpetual licenses are available for the on-premise edition.
Microsoft provides a 40 percent discount on the regular cloud-hosted Dynamics 365 pricing to current Dynamics AX maintenance plan customers.
There are two ways to make a move to the cloud:
From SA – enables you to cancel your current maintenance payments at renewal and move fully to the cloud service.
Cloud Add-on – allows you to keep paying your Dynamics AX maintenance while also adding the Dynamics 365 SKUs at any time.