When does beta become alpha software?

Daft question most probably as it seems obvious. But when do you consider your software at the end of its beta stages and user ready.

I understand that even in production ready is still has the potential for bugs, also if no one is testing your software, except yourself and you don't do unit tests per se, how confident can you be, in it being post beta and now in the production ready stages.

Looking forward to hearing ideas.

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