It seems like my clients get different ip addresses everytime they request a dhcp lease from my asa 5505. I guess it's not a problem but is there a way to at least try to supply the same ip address to a returning client?
Increase the DHCP lease time, the default is 3600 seconds.
you can set it somwhere between 0 to 1048575 seconds.
For your case , set it for 24hours with the command :
dhcpd lease 86400