I have a legacy purchase on an app that is not restoring. I have a receipt - can someone guide me in getting it restored please? Thanks :)

Hey.

I purchased a lifetime subscription for an app in 2017. It has been referred to (by its developers) as a legacy app (because they charge yearly fees now). It is currently not restoring after an update and the developer site recommends contacting Apple to resolve. I have a receipt.

Can someone point me in the right direction please?

thanks!

Melanie