This happens when they no longer want to sell or support an app, or when they release a new version that's such a major change that they treat it as a separate app.
Nke a na - eme mgbe onye mmepụta ahụ anaghị achọ ire ma ọ bụ kwado ngwa, ma ọ bụ mgbe ha hapụrụ mbipụta ọhụrụ bụ mgbanwe dị otú ahụ na ha na - ewere ya dịka ngwa dị iche.