You need to be careful with this info. Let's assume the scenario your customer uses SDK 2.8.6:

and imports SDK example project of Hello world:
After importing, customer can see an info Erich has mentioned above:

Then he decides to export the project using Export project(s) to archive (zip) from Quickstart Panel, then sends the zip file to you.
And now funny part: you are using SDK 2.9.3:

and want to import customer project using Import project(s) from file system... from Quickstart Panel. After importing, you can still see Associated SDK - version=2.8.6, so far so good. However, when you restart your MCUXpresso, Associated SDK changes to the one you currently use
I found that the info about SDK is saved in .cproject file, provided with exported project. Therefore, I believe you can double-check SDK version the project has been created from initially:
