There are always a great many questions that people have not addressed in other documentation. This page is an attempt to answer those.
Yes! It does not matter with what store you subscribe to content, it will be available on all devices on all operating systems (including the web client) for as long as that subscription lasts. Note that though the web client can access all subscribed content, there is no way within it to request access to new regions; do that from a Mobile client first.
Deity provides services to both users and publishers and must respect the rights of both. Users expect access to what they have paid for while publishers want to be able to change their content and maybe even (heaven forbid) remove it completely. In the case of free maps, publishers can do what they wish. Users, well… you get what you pay for.
And since we must provide users with that for which they pay, we can’t provide a one-time-forever-access option because then publishers would not have the options they desire. Publishers set the subscription period as they deem appropriate but in doing so agree that the content must continue to be accessible and intact for at least one full subscription period after choosing to remove it from the system.