Ah I see, well I don't think I will buy it as an upgrade, because I don't have many ships, and I intend to keep my 315p :P
Ah, but, for example, I wanted my Retaliator with LTI, so I took a Nox 2 pack, with LTI, and upgraded the Nox Kue to a Retaliator, and the other Nox in the pack to a Vanguard. Now both ships have LTI.
It is the other way to think about buying ships.
So if you bought a Polaris in the most recent Anniversary sale you would have a Polaris with 60 months Insurance, or if you bought a Hawk, during the same sale, and upgraded it to a Polaris (also during the sale) then you would have a Polaris with Lifetime Insurance for the same price.
Further if you bought a Upgrade from a Constellation Andromeda to a Polaris, and had the Constellation you would be flying the Constellation until you apply the upgrade, presumably after the Polaris is flyable, as long as you don't melt the upgrade your price does not increase even if the Polaris price increases.
I know it is complicated. :)