ERC-4907 (Rental NFTs)

ERC-4907, titled Rental NFT, an Extension of EIP-721, was created by Anders, Lance and Shrug of the Double Protocol team in March 2022 and reached Final status on 28 June that year, becoming the thirtieth ERC standard to do so. Its contribution is to separate the right of use from the right of ownership: it adds a user role that grants permission to use an NFT but not to transfer it or reassign users.

The mechanism rests on three functions. setUser(tokenId, user, expires) assigns a user address and an expiry timestamp; userOf(tokenId) returns the current user, or the zero address once it has expired; and userExpires(tokenId) reads the term. The UpdateUser event fires when the user or expiry changes. The key design choice is that revocation is automatic when the date arrives, with no second transaction needed: it was the first standard to revoke the right of use automatically.

It enables renting and lending utility NFTs without custody or transfer, lowering cost and integration overhead. The direct cases sit in gaming, renting characters and items for a limited time, and in real-world assets or the metaverse, leasing virtual land. Double Protocol, from the authoring team itself, uses it to rent assets on Decentraland and Warena, and Shardeum documented its adoption.