does original_transaction_id change after 60 days of expiration

I am trying to calculate apple cut, if users days of paid service is more than a year apple reduces commission to %15.

By the docs: If a subscription expires due to a cancellation or billing issue, the days of paid service stop accumulating. If the subscription is renewed within 60 days, the days of paid service resume from the recovery date.

So can i assume if original_transaction_id stays the same user not violated 60 days, therefore if i sum all the (expiration_date - purchase_date) with that id, is it a viable result ?

Thanks in advance.