A Lease time is the lease duration. A client acquires a lease for a network address for a fixed period of time. Throughout the protocol, times are to be represented in units of seconds.[1]
A client MAY choose to renew or extend its lease prior to half of the Lease time. If a client does not extend its lease in the Lease time, A DHCP server sets the IP address as "Expired" and may allocate the same IP address to another.
The Lease time meaning is the amount of time a host can use an IP Address assigned from a DHCP server. Is the host's network disconnecting after elapsing the lease time? Definitely Not.
A host can extend its lease in the Lease time to continue its network using. For example, If the Lease time is 300 seconds, a host that wants to use the network extends its lease every 150 seconds and continues to use connections.