With the Node Registration function you block the required stake for a masternode in a smart contract.
For a Premium Masternode this is 20000 PIRL and for a Content Masternode 10000 PIRL. The amount will be drawn to your wallet and blocked in the smart contract. The explorer will not show that amount on your wallet until you withdraw it again.
You can withdraw the stake at any time back to your local wallet if you decide to stop your masternode.
Here we see the overview of the Masternode Smart Contracts and the locked amount of PIRL.
Premium Node Smart Contract
Content Node Smart Contract
You can do read operations from this smart contracts and you can do write operations like blocking the stake into the contract.