I'm resurecting my post
I'm sorry nobody responded to your original post here.
Currently IPAM does not support historical tracking. We will only give you the current status of an address. This is something we are interested in adding in the future but I can't comment on time frames or promise we will do it.
As a work around, we have a report for all active addresses. You can schedule a recurring report to run to keep records. Obviously this is not an ideal solution but would allow you to see if an address was used or available in the past.
Thanks for the anwser.
I think it's something solarwinds should look at. Many competitors has this option.