Compute Unit is a way to measure your RPC request usage on MegaNode. We provide each MegaNode user a monthly quota of usage, and each method will consume a cost based on the resource required for execution. You can think of this as you have a balance in your account and each method has its own price. This will be deducted from your account upon submission of RPC requests. The price of each RPC method is called Compute Unit. Based on this calculation, we enable our users to utilize the monthly request quota more efficiently. In short, you only pay for what you use.