Keeping track of Customer's status updates

Hi,
whenever a customer is changing its subscription status, I would like for the information to be appended in a specific box/property/field.

For ex. Customer takes a starting-package -->

“subscription type” = “starting package”

&

“subscriptiont history” = “starting package”

One month later, customer changes subscription to premium package:

“subscription type” = “premium package”

&

“subscriptiont history” = “premium package; starting package”