Evaluation mode gives you access to the most robust edition of ESXi. You can use vMotion, HA, DRS, and other features.

The evaluation period is 60 days and begins when you power on the ESXi machine, even if you start in license mode initially rather than evaluation mode. To make full use of the evaluation period, decide as soon as possible on whether to use evaluation mode.

ESXi Installable is always installed in evaluation mode.