The repetitive method behind this relationship involves contract management and database operation.

In contract management, an expired contract can be renewed by mutual consent, which is equivalent to establishing a new contractual relationship, and the old contractual relationship is regarded as expired.

In some specific scenarios, such as in the Redis database, you can set a key with an expiration time. When the expiration time of the key comes, the key will automatically become invalid, thus achieving the effect of repetition.