As you have probably noticed, Oracle has released the 18.104.22.168.0 database which includes the much-anticipated in-memory database option. So far, so good.
Unfortunately, the in-memory option is enabled by default and Oracle expert Kevin Closson has shown on his blog that a developer can trigger the in-memory option by creating a table with the INMEMORY keyword. Ka-ching, your organization is $23,000 out of pocket per CPU at the next license audit.
If you're running 22.214.171.124.0, read Kevin's blog (and disable INMEMORY if you don't need it).