Microsoft project management software used to plan, manage, and communicate a project schedule and other information among workgroup members, project managers, and other stakeholders.
You may want to refer to AI's detailed guidance first, especially regarding transferring the activation and using the Product Activation Portal.
In addition, could you clarify how Project Professional 2024 was originally purchased (for example, directly from Microsoft, through a reseller, or via a volume licensing program)? Different licensing channels can have different activation methods and limits.
Also, when you sign in to the Microsoft account that originally redeemed Project Professional 2024, do you see the Project license listed under your services/subscriptions? Project Professional 2024 is typically associated with the account used when the product key was first redeemed.
Regarding your second question, it is generally possible for Microsoft 365 and Project Professional 2024 to be associated with different Microsoft accounts. The important point is to use the account that owns the Project license when installing or activating Project.
For more information, you can refer to:
https://support.microsoft.com/en-us/project/install-project
I hope this information helps, and if you can provide those details, the community may be able to determine whether this is an activation-limit issue, a licensing-channel issue, or an account-association issue.