We would also keep a hard copy in the unit. 

I have been buying notes for many years and the banks provide me a hard copy of the original loan application.Joe Gore

@Agatha OliveiraSharing an operating agreement does not pierce your LLc and every contract you enter into the company should ask for a copy of the operating agreement to confirm the person signing has that authority

Pick up a copy of James Dainard's new book, the House Flipping Framework. 

Write the property on the receipt and keep a digital copy and the hard copy.Quickbooks Online is a good software for both receipt capture and organizing what expense goes with which property.  

I will be bringing copies of my deal and all of the numbers to share with those who might be interested.

Both Keycheck and Avail.co also keep a copy of the lease and let you iterate it as you think of things that need changing.

We’re one of the few property managers that require W-2’s and a bank statement and we go way beyond the traditional, “income must = 3x rent” qualifier.Below is more information about what our Applications Department does to screen applicants and find the best tenants possible for your property.Required InfoWe require the following from each applicant over the age of 18, that is not a dependent of another applicant (as evidenced on a tax return):Copy of acceptable state picture IDRecent YTD paystubRecent W-2Recent Bank Statement, all pages, no info blacked outRecent tax return if self-employedApplicants are often slow about turning this information in, asking us why we need it and then taking several days to submit.

Here is a copy paste from a post of mine a couple years ago.http://forums.biggerpockets.com/viewtopic.php?

Spend your time on your contracts, insurance, and operations.Contracts-  copy, borrow from someone else as a starting point.