As of next month, SoundCloud will be imposing streaming limits (15,000 plays) on third-party applications.

Here's what they had to say about it on their blog:

At SoundCloud, we're building an ecosystem where creativity thrives. Developers are an important part of that ecosystem. We’re continually inspired by how you use the SoundCloud API to support creators and listeners in innovative ways. But as the ecosystem has grown, we're dealing with an increasing number of applications that abuse creator content. To help us limit this type of behaviour, we're introducing a daily rate limit on API play requests. Beginning July 1, client applications will be limited to 15,000 play requests per 24 hour period. Only a small number of developers will be affected by this change, and we’ll be contacting them via email to ensure a smooth transition.

This only affects tracks played via third-party applications, not tracks played directly on SoundCloud, or indeed embedded streams.