other sources, at least back from 2016, report differently: https://discussions.apple.com/thread/7548819
I just made a test, registered a new app store account, bought an app while on a country, deleted and switched country: the app was even still available in my purchase list and I could download it without paying it again. The two payment methods in the country were different btw.
what kind of in-app purchase is the lifetime subscription (https://support.apple.com/en-gb/HT202023)?
if it’s a non-consumable one:
You buy these items once, and you can transfer them to other devices that are associated with your Apple ID. If you lose a non-consumable purchase, you might be able to download it again for free.
since the purchase will be linked to my app id regardless of the country I would expect to be able to “donwload” it again for free.