The SMPI “Binary” is MIT licensed, the but the source code that produced it is closed source and proprietary.
This means you can use the Binary as part of your product in the same way you use other MIT code, but with the exception that the original source code of the Binary that went into the compiler to produce the Binary as output is not available under the MIT license.
A perpetual license for the source code can be purchased for a small fee.
Please contact firstname.lastname@example.org for details.
The Binary is included in the IO Providers source code repos so you do not need to download it separately.
Why buy a source code license?
Support is offered to paying customers first, although it is dependant on how much free time the SMPI team has.
Make your security team happy
With the source code you can re-generate the MIT licensed binary, and check the hash codes are equal. You can see the chain of custody of all included code.
Make your lawyers happy
A MIT licensed binary with proprietary per business source code licenses is an unusual scenario. You may want to buy a perpetual license for clear legal compliance if you are going to transfer ownership of your software to another owner.
You may want to use SMPI as the foundation for your own custom library.
Increase your bus factor
If the SMPI team all get hit by a bus, there will be no more updates over time. Having the source code will allow custom builds, for example to use a newer SQLite version or extension.