While the files for the Application Server executable program are only be installed once on one computer you can configure multiple instances of the Application Server to be run at the same time on the same computer. I.e. the Application Server may run multiple times on the same computer using different Application Server Databases.

Each Application Server Instance is run as a separate Windows Service and has its own instance configuration. Each Application Server instance must access its own (separate) Application Server Database.

When you install the Application Server using the Application Server Setup Program this Setup Program will automatically create a first instance - this instance is called the primary instance. Uninstalling the Application Server will also remove the primary instance.

If needed you can use the Application Server Instance Setup to install one or more additional instances.  Additional instances are not removed when the Application Server is uninstalled but need to be manually.

An Application Server Instance is uniquely identified by the instance identifier, a string you specify on installation of the Application Server or Application Server instance.

Every instance of the Application Server must be licensed separately.

Warning: Each instance of the application server must be configured to use its own Application Server database. Configuring two instances to connect to the same Database will corrupt the data in the database.