First, it's open source. so it's free technically. And, as all the database miner node is distributed globally(not enought for now). By running a client you can visit the forum even from localhost, it's relatively hard to block the forum. But using database hosted by miners need to pay PTC. You can get PTC by replying to the [topic](https://demo.covenantsql.io/forum/#/t/2) with your wallet address.