Thank you for all pieces of advice. However, could be Office Accounting be activated online in Windows XP? I know that all Office activation wizards require TLS 1.3.
Never tried online activating for like... ages But fun test would be: if you manage to update XP to a point where you actually can communicate with license server, why not? We can generate unique keys, i dunno if Microsoft actually keep tabs on every single key released over the years or if a new unique key not activated earlier is activated and a copy is kept for check later as blacklist. I might try this with a Windows 7 later.
To answer myself I could, using a Windows 7 with Accounting 2008 (SBA 2006 and Accounting 2007 was nagging about compatibility issues) activate over internet with a generated key. So yeah, possible in Windows XP i guess too. I was prompted for registration, so I filled out registration as our "beloved" pontus. (i'm sure that will haunt me later... )
The DOS version hasn't been updated, the last official release is too old. Only the artifacts from this post are. Note: You need a Github account and be logged in to get the downloads there.