We need to be clear here. The licenses on the vMM is tied to the license passphrase generated on the MM at initial startup (a hash if you will). The passphrase is based on the virtual mac of the VMM as well as the UUID (vmware generated). So long as the UUID and vMAC are preserved, the passphrase will not change and the licenses will still work.
vMotion within the same cluster should preserve that as the vCenter will coordinate that amongst the cluster members.
Note it is NOT supported to vMotino the vMMs while running. vMotino requires that all databases be quiesced to prevent any corruption or loss of data, but the databases on the vMM do not support qiescing and are not exposed even if they did. So vMotioning a live MM is done at your own risk. Halting and shutting down the vMM before vMotion should work fine, but as always back up everything before doing so to be safe should anything occur.