Sold a company.

I learned A LOT in the process, main one being that you should keep meticulous and separate records for anything that has the chance of being spun off. The company I sold grew out of my freelancing but was separate with a separate name. Unwiring the financials as well as the logins and everything else was a headache. It also looks better to your buyer if you can quickly produce accurate records on sales. I had to back-track and re-calculate several times, leading to more back-and-forth than was necessary.