Upload Space

I am looking at my upload space and it looks like it has reached it's limit or close to it.  I am on the free plan because we do less than 100 submissions per month.  My question is, is the space limit per month or overall?  Please let me know because I have an integrated spreadsheet we use to keep our numbers and I don't want to lose the data.  I appreciate your help.

Thank you,

Bryce