I realize this post is 2 years old but someone may have the same question.I use Microsoft One Note for Desktops, it's free and stores your notes in notebooks with tags that are easily searchable for reference later.I have notebooks for Note Investing, Real Estate Investing, Information Technology, and Digital Marketing.Usually, something that I'm studying falls into one of those categories and each notebook has subcategories. 

Big developers where not investing as much anymore, land flippers where left with unwanted inventory and if you for example now wanted to do an agricultural business and bought land in some places, the math would never makes sense.The good thing is as you mentioned some small towns are thriving because of the expat presence, similar to what happens in the US with "gentrification" the expats attract the digital nomad crowd that works from the beach, surfs, love great coffee shops and restaurants etc.

If I provided all of the information digitally, maybe I would keep a digital copy for ~6 months after the sale if the new buyer reached out for any reason.

Digitize physical receipts for easy storage.

@Deirdre Lizio thanks for the tips on foreign taxation, however that should not be an issue for us as we are not actually planning to stay in one place but rather be digital nomads.

The free option is good enough for tracking basic payments and expenses, but paid service makes digital leases and advertising very simple. 

Tourism, remote workers, digital nomads, snowbirds, retirees, near shoring induced economic boom, growing middle class, massive population (growth) and geographical location.

Note I have 8 digits of local RE and my net worth increases over 7 digits per year for at least the last handful of years.  

A lot of great options out there for self-managing if you decide to go that route; aside from providing the basics (listing, tenant screening, digital lease creation, rent collection, and maintenance tracking) some services also offer your tenants additional capabilities which makes it an easier sell on your end when getting them to transition over (ie. their ability to report on-time rent payments to the credit bureaus).

And I find it funny persons are all too happy to take a 6/7 figure action on "A" persons declaration of comp/what the #'s are but no-way do they trust "A" contractors 3,4,5 digit project numbers, no-way no-how no no no, gotta get 3+ bids right.....