Matt,
Last night I was one of those who had problems because your server was not available. I couldn't understand why because I did upload the locale license file that I was emailed last week. I had read somewhere that it should be put in the root directory of the WHMCS installation so that's what I did.
This morning I read on WHT's forums that it should be in the "include" directory. I moved it but now I have no way to test it. This was a very bad time for me since a friend had just told me he was gonna shut down his VPS and send his clients over to me. If one had tried to create an account last night I would have looked pretty bad. I need to make sure that this doesn't happen again so I have a few suggestions for you that I hope you will consider seriously.
1: Add a small chapter about licensing in your documentation. There is nothing that explains it. When I got my keys for the first time last week that was the first I ever heard of it and I didn't know exactly what to do with it.
2: Change the email that sends the new keys to add instructions on what to do with it. Your email says "Please unarchive and upload this file to your installation.". Change that to specify WHERE to upload it.
3: There is no way for me to know if my local key is working. I will only find out on the next time my server can't reach yours. There's 2 possibilities I see here. Change the admin panel to verify that a valid key exists and display a red warning on top of the page if it doesnt or, simply add an option to the tools to validate the local key.
These 3 can be implemented very easily at a minimal cost to you both in time and money. In the meantime, please give me a way to make sure my local license will work the next time your server goes down, I can't risk looking bad like that again.
Thanks.