EEA or European Union driving licences are recognized in Austria, and may be converted at any time on a voluntary basis (this resembles the process of issuing a duplicate of a driving licence Duplikatführerschein).
Foreign driving licences (not EU or EEA countries) which are valid have to be re-registered. A driving licence must be re-registered within six months in the area in which you live. The responsibility lies with the driving licence authority (in towns this is the federal police headquarters Landespolizeidirektion, in smaller communities the district commision Bezirkshauptmannschaft, In statutory cities like Villach: the Municipal Authority Magistrat).
More information: here.