Stand alone app PDM logoff

Is it possible to logoff from PDM after ending a stand alone app?

Actually there are more seats then available contributor licences.

The stand alone app purpose is to get latest version of DXF files in the vault for importing into the Lantek’s (sheetmetal CAM software) database.

After importing the DXF files the licence must be released on app terminating for example.

No. There is no API call for log off. If you do not have enough licenses, consider creating a task add-in that runs on your server to off load all the API code to one instance and one license.