What product can I get by with?

I do missionary work over seas and need to convert PDF's into word to edit.  I am non-profit and need to do this as inexpensively as possible.  I down loaded Acrobat DC trial and it certainly does the job.  I was hoping that there may be another version that is less expensive.  I see a student/ teacher version of DC; but I do not know if I would be legal using it.  Any thoughts or ideas?