What's the deal with receipts? Legally, you're required to keep receipts for your business purchases for 7 years.
What's the best way to do it? Some choose to use expense softwares, but my preference is to keep it simple. I advise my clients to make a note on the physical receipt, snap a photo with their phone, and carry on with their lives.
Once a year, I recommend upload the pictures to a free Google Drive, leaving them there in case of an audit.