For a one-time registration fee of 0.01 NMC, which is around 0.015 USD in 2021, you get a domain registered on the Namecoin blockchain, valid for 36,000 blocks, which is more than half a year. After this period, the renewal takes about 0.0004 NMC, which is just the miner’s fee. Your ownership and access to modify the value data for your domain are cryptographically secured by your wallet’s private key.