Memory expansion

Dear people,

Anyone can please explain to me, what exactly does the feature "Memory expansion"?
I have a WC log with, let's say 120 Fuzzy matches but I have no TM for this project.
I asked my customer about that issue, and he said that the fuzzies are generated by "Memory expansion"...:confused:

Thank you in advance

I think that if you have the autopropagation feature enable, then it happens what you are saying... fuzzy matches appear from repetitions in the document.
Cheers!