The short answer
The file is yours as soon as the order is paid. There's no separate "buy out the file" fee, and no requirement to order printing as well just to get the file. If you only ordered a scan, the scan file is yours.
What format
Standard exchange formats you can carry into any ordinary software: a mesh comes as STL, OBJ or PLY, a CAD model as STEP or 3MF, a virtual tour as a shareable link. Nothing gets locked to my software.
Why it's this simple
Because otherwise you'd be dependent on me for every next step, and that isn't honest business, it's a trap. If you want to take the file to different 3D software, a different printer or a different company, that's your right. The only thing I lose is that you might go elsewhere next time — and that's a risk I'm happy to take.
What stays on file with me
By agreement I keep the processed data, so you don't have to commission the work again a year from now if you need another print of the same object, or a fresh export. Retention is agreed as part of the order. If you want the data deleted the moment the work is handed over, that's what happens.
Ask freely if anything about the files is unclear.
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