Customer just bought an Oracle license - am I allowed to install Oracle 11.2.0.4 without support contract?
You can install the latest version available at the time of purchase, but no newer versions after that.

The "funny" part is, these versions (like 11.2.0.4) can be obtained from https://support.oracle.com/, but you can not download them, because you do not have a support contract. In this case, when you request the installation media, an Oracle representative goes on-site with the requested software (just an example I know of, there may be other ways).

This part took quite long the last time I was in such a situation with a customer.

Without a support contract, you can not download patches, and you can not open service requests. When you hit a bug, you have to live with it or apply an acceptable workaround.