Do trial periods carry over during subscription upgrades? For example, if I were to upgrade from subscription A that is currently within its introductory offer (free trial) period days to subscription B that also has the same introductory offer setting, would it be like a regular upgrade where purchaseDate and ExpiresDate remain the same? The reason I'm asking is because from my previous understanding, free trials can only be applied to a subscription within the same subscription group once. So when I do an upgrade like above, I expected the trial offer to be used on subscription A already and hence subscription B should no longer have its offerType = 1. But as far as testing shows in the sandbox environment, after being upgraded subscription B retains the same "trial period". I would like to know if this is the correct behavior, and also if there are other patterns outside of upgrades that would behave the same.