Salesforce Survey is available in Health Cloud & Financial Service Cloud otherwise its paid. Community Cloud is also required to use Survey. If you need to practice Survey, create a 30 day trial org from this URL (mentioned in this trailhead module). One Survey can be created and used in Enterprise and Unlimited edition, so if you need only one survey then its free. In my case, I had to send same question to every customer on Case close , so it was free.
Prerequisite to use Salesforce Survey
Step 1 – Enable & create Community. Once community setup is done, we would need to activate it. Community can be created by any template. It can be blank as well, if it’s being created only for survey.
Step 2 – Enable Salesforce survey by navigating to Admin setup. You would need to select Community, which would be used by Survey to compute public unique link.