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Renewals

Once minted, an expiration is set onchain for any key. The expiration is a timestamp which can be retrieved for any individual key by using the keyExpirationTimestampFor method.

Once expired, a key is not considered valid anymore, and functions like balanceOf will not return a key that can be renewed, and its expiration extended.

An expired key can be renewed. When it is renewed, the key's expiration date is extended so the key is considered valid for a longer duration.

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No new keys or membership tokens are created upon renewals.

For renewals and extensions, each NFT needs to be extended individually. However, they can be extended using different methods:

  • extend where the sender of the transaction pays for the extension, even if they are not the owner of the NFT itself.
  • renewMembershipFor which can only be called for ERC20 locks where the owner has approved the renewals through an ERC20 approval as their balance will be reduced.
  • grantKeyExtension which is similar to grantKeys and can only be called by lock managers or key granters.

Automated renewals​

The renewMembershipFor function enables automated renewals! In practice, anyone can call this function on an expired membership NFT, provided that the current owner of said NFT has approved a large enough amount of ERC20 to be spent for the renewal to succeed. The contracts also include a function isRenewable that can be used to check if a given membership can be renewed. This function reverts with an explanation about why a given membership cannot be renewed if it is indeed not renewable.

Unlock Labs has built scripts that will automatically renew expired keys on all the supported networks.