Just my 2 cents, but I think you should host the legacy installers. You'll have to take some trouble to make it clear that they're unsupported, and made available only as a courtesy to legacy customers. But why not do it? People are bound to lose the one they downloaded and it seems harsh that they own a perpetual license to the software, and you have a copy of it somewhere, but they have no way to access it.

Otherwise, what's the value of having a perpetual license?