Answer:
Moving authorizations is initially only possible with administrator rights; see Image 01.
Furthermore, a user can only move the authorizations between online licenses; that is, RFEM 6, RSTAB 9, RSECTION 1, and RWIND 2. You can find an overview of your existing online licenses in your Dlubal account under "Licenses" → "Licenses" → "Licenses"; see Image 02.
Before moving the authorization, make sure that it is not active at the time. You can check this under "License Sessions"; see Image 03.
To move the authorization, go to "Licenses" → "Authorizations by License" and select "Source License" in the "License ID" drop-down menu. All existing authorizations will be displayed. Then, select the "Target License" in the drop-down menu of the corresponding authorization that you want to move; see Image 04.
In the example, the authorizations of the "Structural Stability" and "Steel Design" add-ons have been moved from Online License 03 to Online License 02.