Final answer:
The registration to engage in collaborative drug therapy management expires when the specified time period for the registration ends.
Step-by-step explanation:
The registration to engage in collaborative drug therapy management expires when the specified time period for the registration ends. The length of this period may vary depending on the specific guidelines and regulations set by the governing body. For example, in some states in the United States, the registration may need to be renewed every two years. However, it is important to note that these regulations can differ from one jurisdiction to another, so it is crucial to consult the specific requirements in the relevant jurisdiction.