The zip-file of the registered PL/SQL Developer 4 version (the latest 4.0.x version is 4.0.3 by the way) contains a plsqldev.exe and a readme.txt file. The readme contains a description of the installation procedure. All you need to do is extract and run plsqldev.exe though.

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Marco Kalter
Allround Automations


Marco Kalter
Allround Automations