AWSCore uses Bolts framework as the main promise engine, as you can see here https://github.com/aws/aws-sdk-ios/blob/master/AWSCore/Bolts/AWSBolts.h.
In the source code of that file shows
* Copyright (c) 2014, Facebook, Inc. * All rights reserved. * * This source code is licensed under the BSD-style license found in the * LICENSE file in the root directory of this source tree. An additional grant * of patent rights can be found in the PATENTS file in the same directory.
that patents file is here https://github.com/BoltsFramework/Bolts-ObjC/blob/master/PATENTS
If you want a refresh about the BSD + Patents, look here
This is obviously only a fraction of the whole SDK, but it is widely used across different classes.
Look for example the
- (AWSTask<AWSAPIGatewayResponse *> *)invoke:(AWSAPIGatewayRequest *)apiRequest;
Every time you call the APIGateway function it returns an AWSTask. That task code is licensed under the BSD + Patents. So every time you communicate with Amazon servers using that function, you are accepting the license.
I doubt amazon will rewrite their SDK only for this issue, It's more likely that Bolts update its license, I hope so :).