Since applications on the ServiceNow store are purchased at a company level and not a user level, all of the purchase related information for the company can be seen in the "My Store Activity" Page. Any user from the company would be able to see this information in the store by logging in with their valid HI credentials. However, if a person were to leave the company and wanted to manage their notifications in a way such that it can be transferred over to another admin user, there is no way to transfer personal notification settings on the ServiceNow Store App. The person who takes over would have to manage their own notifications.
To see how to Manage Notifications on the Store App, please refer to the following