Stellar is a commercial software company. While they offer discounts and occasional giveaways, there is no universal "master key." Files claiming to be a Stellar Converter for OST activation key generator are almost always:

Run the "Smart Scan" algorithm. The activated tool rebuilds the OST’s B-tree structure, even if the header is destroyed. It recovers deleted emails (marked as Permanently Deleted) that Outlook hides.

Use the "Advanced Filter" (Date, From, Subject, Attachment type). This is critical for eDiscovery and legal hold exports. The free version disables filters.