I don't think that's a grey area at all. If you paid for it, you should be able to keep it. It's yours. You own it. Period.
Didn't read the TOS, I see.
You gave them money, but it's not a purchase in an ownership sense. You're buying a "Digital License" that the seller can dissolve for any reason, same as with a Kindle eBook or movies on Google Play.
You bought something, but not what you think you bought. Instead of buying a product, you purchased a license to
use that product.
Very few digital retailers are in the business of actually selling ownership rights of any digital product, and the reason is piracy -- there's very little stopping someone in such a world from duplicating and redistributing the digital files because they "own it".
Ownership of digital files is an incredibly complex topic, legally speaking, and what we have in play now is a tangled mess of nasty unpleasant compromises to make it even sort-of work.