I have never seen this information in either the CLI or the GUI. I think you would have to review the log files to find stop and start date and time. Easiest if you export the log files to a syslog system like Splunk.
When creating a DHCP Fixed Address, you have these options: MAC Address DHCP Client Identifier It does look like you can fix an IP to a client by the Client Identifier. You would have to test it out to see if it works.