About ocr quality

I am a online user for kami, and I meet a problem about ocr function.
I try use it and find the file after ocr will loss some quality.
My document is scanned under dpi 300, and seems the online ocr will
change its dpi to lower.
Is this the limited function for online users without paid?
And If I paid one month for basic function, is the orc quality will
become more precise? Thanks a lot.