You can set a supply on an NFT you create on Cent to limit how many copies of the NFT can be collected. In the release flow you will see an input next to the editor labeled supply.

NFTs that do not have a price set must have a supply between 0 and 100. The supply cannot be greater than 100 for free NFTs. NFTs with a price can have a supply between 0 and 10,000. If you leave the input blank the supply will default to 10,000 NFTs.