What should I do with my LSWS license if I change my server IP?

It depends on your situation.

If it is on the exact same server but only IP change, there is no further action from you. Our license system will update the license ip record automatically when your server communicates to our license server overnight.

However, if you are migrating to another server with new IP, you will need to release license first from your WHMCS account and re-register the license on your new server. Please refer here.