Once I secure that property I will look to do a lease-to-own agreement.

The name implies it is just extending an agreement. 

I'm going to have them sign an agreement for a non-refundable deposit of half month's rent, then apply it to the first month of rent if they end up closing.

I run my short-term rental business out of my personal house under my LLC, which I drew up a lease between that creates an agreement to pay for utilities, internet and common household products I need to function my business in exchange for the property.

(This is someone who knows what I can do and trusts me to do what I say I'm going to do, however I want to be professional in every aspect)Should I seek an attorney to draw one up for this agreement?

If it is in there, you are out of the agreement and can sell to someone reputable- heck post it on BiggerPockets Overall, if all things are equal, keep his hand money and walk away/fin$ another buyer.

I will need to research that more.As for a Lease Purchase agreement, I don't think he will go for that. 

If that was stated in the broker agreement the consumer signed and then that was on file with that specific lender, then yes, it'd be legal. 

So, I have a tenant that is moving in on 2020-10-01 and we have already gone through the whole pre-screening, interview, application process, background/credit check, signing the lease agreement, everything was great. 

Residents will leave when they need to leave, regardless of agreement terms.