Thank you for your interest in our products and services.
The answer depends on what you actually need, which is not completely clear from your question.
1) If you need to embed an OPC Client into your software, so that you can connect to OPC Server and read/write values of data points located in them, you can use our QuickOPC-COM product, and consume its objects from C++. The trial version of this product you can download from our Web page, and commercial licenses are available, including "Runtime Free" licenses.
2) If you need to embed an OPC Server into your software, so that it exposes data points and OPC clients can connect to it and read/write values, then we do not have a product as such for you, directly. We have, however, a so-called "OPC Runtime Kit", which is a set of C++ classes for developing OPC Servers. We use this library extensively in writing OPC servers of our own and for our customers. You can only get this library if we develop the server for you or together with you, as custom work.