In order for me to correctly answer this question, can you please clarify what you mean by community? Sometimes Jive users use that term to mean the Jive site as a whole, while others use it to refer to a specific Space or Group within the site.
Thank you for your reply,
When he talk about community, he refers to a specific Space or Group within the site.
He is a community manager of a specific community (he has all the rights to his community) and would like to know the dates of subscription of his users to his community. For example, its objective is to thank the 100th subscribe.
That depends on what you mean by the term subscribe. Jive doesn't have a construct known as subscription per se, so my assumption is you are either referring to Following, or you're referring to the concept of a user joining a Group or Space (aka becoming a Member of that place). If you are referring to the former, unfortunately there is not an out of the box way to track when someone follows a Group or Space. If you're referring to users joining a Group or Space (which is only possible if that place is private), then the community manager can achieve this by going to the Manage dropdown in the top right corner of the place, then clicking "Members". This will show the list of all members of the place, along with their join date.