Thanks Nathan
The only limit to NATSlite is that if you go over 300 joins in a billing month we will invoice you for NATSPlus at $350/mo on your next invoice. They're not limits in any way as fabian said, it's simply invoicing tiers to help smaller/newer clients get on board and use NATS to help their business grow.
The billing tiers are as follows:
NATSlite up to 300 joins/mo, $150/mo
NATSplus up to 750 joins/mo, $350/mo
NATS unlimited joins/mo, $650/mo
In the past we had a limit on the number of sites we allowed on the 2 lower tiers but we have since dropped that limitation and you can have as many sites as you would like on NATSlite or NATSplus.
Hope this answers your question further.