ReSharper Ultimate is a license that combines individual JetBrains .NET tools, as well as ReSharper C++.
Each ReSharper Ultimate license allows a single developer to use ReSharper, ReSharper C++, dotCover, dotTrace and dotMemory.
If a single developer uses Visual Studio to code both in C# (or VB.NET, or TypeScript, or other languages supported by mainline ReSharper) and C++, they would want to have ReSharper on hand to help them out with both worlds.
Purchasing ReSharper and ReSharper C++ for this developer is a valid option but buying ReSharper Ultimate will actually cost you less than the two-license combo and will additionally make the developer eligible to use dotCover, dotTrace and dotMemory.
Developers don't always care too much about performance bottlenecks, memory leaks, and proper unit test coverage until late in the development cycle. Having familiar tools at hand is an important prerequisite to confidently solving performance and memory consumption problems as they arise.
dotCover, dotTrace, and dotMemory are only licensed as part of ReSharper Ultimate, and even if these products are not put to practice every day, you might want to make sure that they are readily available when it comes to the crunch.
Until recently, JetBrains .NET tools have been distributed using different licensing schemes, which could sometimes introduce unnecessary confusion for customers with multiple licenses.
To make things easier, a ReSharper Ultimate license covers many of the tools that can then be maintained without duplicating effort. You won't have to monitor subscription expiration dates separately: just use the latest releases of all the included tools for as long as your ReSharper Ultimate subscription is active. As soon as it approaches expiry, just renew all the covered products in one go.
Yes, your existing licenses to any of these products makes you eligible to purchase new ReSharper Ultimate subscriptions with an additional discount.
ReSharper Ultimate makes you eligible for all updates across all the tools that it includes for as long as your subscription is active, which can be any term from 1 month to several years. You can renew your subscription to continue using the most recent versions of the tools, or, if you stop renewing after at least a year of continual subscription, you're eligible for a fallback perpetual license to all the tools. For details on how JetBrains subscription licensing works, please see JetBrains Toolbox.