Online Services available even if there are no Licenses issued

Thomas_Steibl, the last time I checked, access to SharePoint is granted to synced users by default. No licence required. It is that certain functionality of SharePoint is deprecated for licensed users.
What you need is to explicitly block access to SharePoint for users. What has worked for me in the past is

1- make sure none of the sites have blanket access (eg access to Everyone, or Everyone except external user)

2- Create a security group with all the users who should have access and grant that group access appropriately

Same goes with ODFB