Question:-How do I implement a system which tenants cannot access the wifi without my permission. ie: like a hotel giving you a time expiring code?

There was a lease, but it expired in November and we are month to month because the landlords know I made an offer on a short sale which has been delayed. 

That would be an idea but for now most of my tenants lease dont expire for at least 8 more months. 

Maybe once you've built a relationship you can talk to that broker and see if you can help sell one of their difficult listings by wholesaling it after the contract has expired.

The day of contact expiration November 26, 2018, he informed me he wanted he had a buyer and needed me to sign some documents.

The listing was about to expire, The agent was fed up with the seller, the seller was out of state, in tax foreclosure, inherited the property and there was title defect we were wiling to accept. 

By the time we had closed the previous owner had lived in the house over a year and their ROR time had expired.

Mechanics liens typically expire much quicker than mortgage or judgment liens.

based on my experience with ESA'sin Arizona  if it's not HUD/ Section 8 I'd deny them but if they are getting assistance I'd first ask for the doctors note ( these expire annually) and call your local rep to verify the HUD standing on them. 

I want to see all activity including actives, expired and solds so I can come up with my own numbers and not be disappointed because I relied on someone else's opinions.