You can use it for development purposes. Any other purpose means purchasing a license. On the download page is a link to the license agreement that states:

You may not:

• use the programs for your own internal data processing or for any commercial or production purposes, or use the programs for any purpose except the development of your application;
• use the application you develop with the programs for any internal data processing or commercial or production purposes without securing an appropriate license from us;
• continue to develop your application after you have used it for any internal data processing, commercial or production purpose without securing an appropriate license from us, or an Oracle reseller;
• remove or modify any program markings or any notice of our proprietary rights;
• make the programs available in any manner to any third party;
• use the programs to provide third party training;
• assign this agreement or give or transfer the programs or an interest in them to another individual or entity; - cause or permit reverse engineering (unless required by law for interoperability), disassembly or decompilation of the programs;
• disclose results of any program benchmark tests without our prior consent.

The first two points are the most relevant.

On the Coherence download page it says you need to agree to the Oracle Technology Network (OTN) License Agreement to download the software.

That license contains this text:

We grant you a nonexclusive, nontransferable limited license to use the programs only for the purpose of developing, testing, prototyping and demonstrating your application, and not for any other purpose. If you use the application you develop under this license for any internal data processing or for any commercial or production purposes, or you want to use the programs for any purpose other than as permitted under this agreement, you must obtain a production release version of the program by contacting us or an Oracle reseller to obtain the appropriate license.

So it s a free download only for development purposes. (Most Oracle Products are available free to developers.)

But if you want to use this code in production or in a product you re selling you will need a license.

Have you considered using Infinispan as an open source alternative to Coherence?

Don t forget that the version that you download from the public website is usually just the major release. The minor release, with all the many bug fixes, is only available if you have a support contract.