ITSupportPanel is licensed on a month to month, no contract basis. You purchase ‘agent packs’ based on the number of devices you have under management.
For example, if you have around 600 Desktops/Laptops/Macs under management and you don’t want to cover Smartphones, then you would purchase the 1000 Agent Pack. This would give you buffer as you grow to keep adding more devices. If you realized you wanted to cover Smartphones which would add another 600 nodes, you would then go to the 2500 pack. At that point you may never need to buy more licenses until you grow big enough.