(Android) does it take internal memory space to add games?

[N4pstablook]

Hi i am new in ppsspp, and my english is not the best but i hope someone here could help me..
Please enlighten me,
My phone has 32gb rom, before using ppsspp there was 7gb free space.
Then i use ppsspp and downloaded some games (iso files), the thing is i put my iso files in external memory card.
And i was a bit surprised when i checked on my file manager that it says my internal memory had only 2,5gb free space left.

So again my question, does it take internal memory space whenever i play new games? Even if i download and save my iso files in the external memory card.
Thank you!