Office365 retention policy and their affect on storage

[TherealKillerbe]

I am wondering how retention policies affects the storage consumption in the various Office365 services, once the license is removed. I read following (older) article, But it does not explains the situation once the Office365 license is removed from the mailbox under retention.

We want to use retention policies for people being absent for a longer period of time (inactive mailbox), or have left the company. This says we can, however i have read that this affects the storage quotas assigned to your Office365 tenant.

[#2]

You can use Inactive mailboxes without any additional effect (there is no overall Exchange Online "quota"), but keep in mind that provisioning an Inactive mailbox requires the user to be deleted. Which might have a lot of undesired implications if you are going to reuse the same ID later on.