Hi,
We will inject any specific LSI keywords provided by customers -but we don't do any specific LSI keyword research using any tools or such. Because our writers are native english and actually research the content they write on, a lot of LSI keywords do make it in to the content naturally through writing on the subject.
I think LSI is a bit over complicated -what google is looking for is good, useful content. The use of related keywords and terms is one way Google separates content that is actually researched and meaningful for the market/industry it covers, from the ones that are not. I know some sellers advertise using software or keyword tools to artificially inject additional keywords in to the content as LSI to hide the fact that their writers:
a) don't even spend a minute researching what they write on
b) are not native english and thus won't have a natural affinity to choosing meaningful contextual terms
I think doing that actually backfires, because every Google change is made with the intention of rewarding human written, researched and naturally flowing content.
We write good, well researched content that naturally includes related keywords and terms through researched writing -we just don't use any "proprietary" software or spend hours of digging in keyword tools to do it.