Active/Activation Date of Domains

Activation date for a domain indicates the date and time when a domain was activated (mutated to status ACT) in Openprovider.
You can find this information documented at: https://doc.openprovider.eu/API_Format_activationDate 
Change of "Activation date" is triggered automatically for a domain at Openprovider in following scenarios:
Domain renewal (also in case of renew is a part of softRestore operation)
Domain creation
Activation after create domain (REQ->ACT)
Activation after transfer domain (REQ->ACT)
Trade domain