Power BI licenses

Thanks for NandanHegde and pallavi_r's concern about this issue.

Hi, marzanc01 

I am glad to help you.

Viewing Reports with Different Licenses:
Power BI Pro License: Users need a Pro license to view reports shared with them if the reports are stored in a workspace that is not in Premium capacity.

Power BI Premium License: If the reports are stored in a workspace that is in Premium capacity, users with a free license can view the reports. This is because Premium capacity allows for broader sharing capabilities, including to free users.

Viewing Reports Created with Pro License After Upgrading to Premium:
Yes, users with a free license will be able to view the reports you created while you had a Pro license, provided those reports are now stored in a Premium capacity workspace.

Modifying Reports with a Free License:
No, users with a free license cannot modify reports. They can only view the reports. To modify reports, users need at least a Power BI Pro license.

You can check out the official documentations to learn more about the above:

Power BI service features by license type - Power BI | Microsoft Learn

Share Power BI reports and dashboards with coworkers and others - Power BI | Microsoft Learn

Transferring Ownership of Reports:
Yes, you can transfer ownership of reports. This is typically done by reassigning the workspace where the reports are stored to another user with the appropriate permissions.

Transferring ownership of reports in Power BI Serv... - Microsoft Fabric Community

I hope my suggestions give you good ideas, if you have any more questions, please clarify in a follow-up reply.
Best Regards,
Fen Ling,
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.