The activations take place on the wyDay servers. If you want to run LimeLM on your own servers that's certainly possible.
Our uptime is around 99.97% (we're working on improving it), we have servers on both sides of the country (USA) in case of a natural disaster on one side of the country. We have other redundancies as well. if you tell me what you're looking for I can be more specific.
In short: we take uptime very seriously.