The code in isam.jar and isam-vms.jar is under Apache license.

The code in isam-bdb.jar is available under either Apache license or AGPL license.

This is not my choice, but due to BDB license.

Berkeley DB (BDB) is dual licensed under AGPL and a commercial license from Oracle.

I strongly recommend seeking legal advice on implications from these licenses
before using BDB. But this is my understanding as a non-lawyer.
 
If you have a commercial license from Oracle then you can take code in isam-bdb.jar
under Apache license and use whatever license you want for your own code.

If you have taken BDB under AGPL then you need to take code in isam-bdb.jar
under AGPL license and also use AGPL for your own code.

The code in isam.jar and isam-vms.jar are not linked with BDB in any way and
can be used under Apache license no matter what license you have taken BDB under.