By adding a OEM Product ID to a document it connects the document to a specific server and the document can therefore only be accessed from that specific server. To be able to use OEM Product ID an OEM Partner license is needed.
It is possible to add this protection when a new document is created, click on Add OEM Product ID then choose one of the OEM ID's that is connected to the license.
It is also possible to add the OEM Product ID on an existing document under Document Properties: Server page. Here it is also possible to remove the OEM Product ID from the document. For more information see Dokumenteigenschaften: Server.
Under User Preferences: License page it is possible to add or remove the option to use the OEM Product ID in the documents. For more information see Benutzereinstellungen: Lizenz.