Support
Most questions are answered below. When you write, include the engine version from Settings → About.
I bought Pro on another phone.
Settings → Restore purchase. The store remembers; we never had an account to ask for. After a restore, Pro works in airplane mode too.
My book gives a different Iz.
Type it in the ampacity check — your value is always free and always wins over the bundled subset. The cable-size screen has no typed Iz because a walk across sizes needs a value per size; "Type Iz instead" takes you to the ampacity check.
The limit doesn't match my edition.
Pick Custom in the limit selector and type yours; the verdict uses that number. Then tell us which edition and clause, so the pack can be checked.
Decimal comma or point?
The pad follows your language (comma for Dutch, German and French). Change it under Settings → Decimal separator.
Where did my history go?
Free keeps the last 5, Pro the last 50; the oldest is replaced and a banner says so. Uninstalling removes all history — nothing is stored anywhere else.