I have seen multiple members here facing issues with requesting API keys or having a stable API , I really recommend switching to Blocktrail as It's the best so far when It comes to almost everything compared to other API providers.
I agree. I've personally used both APIs and Blocktrail is much better in every aspect. It support test network for developing and much easier integration with no waiting time for them to approve your key. But in case you want to stick with Blockchain their keys are manually approved and I've read that you must have valid website/domain