I've only had experience with the lite/full license thing once (we unknowingly received lite 2000's instead of the full 2000's). Anyway as I remember you have to go to
https://support.cambiumnetworks.com/licensekeys
and enter the keys you bought there to get the keys you need to put on your radio. As I recall the cambium management thing retains all the keys for you and they are tied to the MAC addresses of the radios right ? So unless the MAC has changed on the radio shouldn't you be able to just log into the license center thing, find the key you applied to that radio and copy/paste/apply it back onto the radio ?
EDIT: Also, the one time we did have license related weirdness with a radio I had to go to the site, factory default and re-configure the radio to straighten it out. You may have to power cycle, and default the radio, to get it to work right. Also note that the 2000 we had this problem with wasn't a lite , it didn't even claim to be a lite, it just rebooted one night and wouldn't allow max connections to be set above 10.