Final answer:
EA customers can purchase M365 add-on licenses at any time during their EA term, but often do so during their annual True-Up period.
Step-by-step explanation:
An Enterprise Agreement (EA) customer can purchase Microsoft 365 (M365) add-on licenses at any point during their EA term. However, it's important for customers to review their existing EA terms and conditions, as adding these licenses will affect their overall licensing commitment to Microsoft.
Often, customers choose to add M365 licenses during their annual True-Up period, which is the anniversary of the EA, but purchases can be made at other times if necessary. It is critical for EA customers to coordinate with their Microsoft account team or partner to ensure that they remain compliant with the terms of their agreement when making these additional license purchases.