If you are renting out one or both sides, you can bill back for water usage, even without a second meter. 

Utility company can tell you the usage for that day.

As you are living in one unit, you will receive personal usage and distribution from the partnership.

You can go to the meter at 4:00am measure the usage for an hour and see what the waste is assuming it is running.

On the pricing page, it's mentioned that PRO perk is to get free RentRedi software, but on the member perks page, it's only a 40% discount.Has anybody successfully gotten the free rentredi usage?

They do this by adding you on to one of their 'perfect' credit cards that have a high limit, usage, and also paid off every month.  

A window frame is damaged I believe it is caused by inappropriately operation.

@Shawn Mcenteer has good advice as MTR may be more safe, but also longer stays which would restrict your usage.

You may want to consider asset protection for the consulting business and/or real estate by holding in appropriate entities, especially depending on how risky the consulting is and how many assets are attributed to that business. 

If the landlord is paying any utilities that are based on usage such as water, then I might discuss a rent bump to compensate for the anticipated increase in usage and address that with the lease update adding the person as an occupant.