Changing your Office 365 Plans
You can change your Office 365 Plans for ALL or a subset of USLs any time during the term of your subscription. For example, if you had a component plan, e.g.,. Exchange Online (Plan 1), subscription with 100 USLs and you wanted to move all users to a suite plan, e.g., Microsoft Office 365 (Plan E3) subscription, you would take the following steps:
If you want to change plans for only a subset of the users (e.g., in the above example you want to change plans for only 50 users) then you would still perform steps 1 and 2. In step 3 you would call support to reduce 50 USLS in the Exchange Online (Plan 1) subscription. Our support agents will waive cancellation fees when these changes are related to an upgrade in your plans.
Additional Resources: Office 365 Support Guide