A group of Microsoft Products and technologies used for sharing and managing content, knowledge, and applications.
Dear Kryptonian_044,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
Based on this article
it seems Business Premium also provided retention policy function.
And retention policy is applied on the site level, but not user level. After policy take effect, any changes or deletion happened on the site which is hold by policy will have a file copy to help retention the files, no matter who is the user edit it or delete it. So it does not require all the users have the required license. But only the user who setup retention policy should have the required license.
You can enable it from https://compliance.microsoft.com/informationgovernance?viewid=retention.
To setup policy on SPO or OneDrive, you can create a new policy from this page
After submit it, please wait for 24 hours for it taking effect.
To learn more about retention policy on SharePoint and OneDrive, you can refer to this article:
Have a nice day!
Best regards,