Abstract: An example embodiment may involve, based on input from an entity, defining, by a computing system, a non-fungible token (NFT) that is associated with metadata representing a value and an expiry time that defines when the NFT expires, wherein the NFT incorporates smart contract functionality to emit an event when the NFT expires, and wherein the NFT is usable by its holder to modify behavior of a software application; submitting, by the computing system, the NFT as an entry proposed for addition to a cryptographically-immutable distributed database; receiving, by the computing system, confirmation that the entry has been added to the cryptographically-immutable distributed database; and listening, by the computing system, for the event, wherein firing of the event causes the value associated with the NFT to be transferred to the entity.