I think you are not talking about ADI license but the PLDS ones.
ADI Licenses are full text to be copied INTO the sysem config, it means if you delete it all the config is empty in terms of licenses, no doubt.
VICEVERSA the PLDS licenses live in a separate xml file, not depending on the system config at all, even if you erase the config (both via manager or DTE) at reboot you will find them all again.
The Serial FK lenght is not vital, the PLDS allows to add "11" to the real Host ID so that you'll have a 12 digits based SD number.
Finally, if your system it's in R11.x but comes from an upgrade path (I mean 9.0 or previous) you will see duplicated licenses, both PLDS and ADI (as invalid), that means that deleting he ADI licenses is not needed.