I stayed at an Execustay in Manhattan for a year once. In NYC it took 6 months to be considered a lease, but they made me pay the tax each month, and after 6 months refunded it all. So you should be getting it all back right at the end. Not sure why they do it that way.
Which Execustay? I believe there are 3. Ill PM you the contact info for the account manager. She was great!
I stayed at the one in Chelsea on 24th and 7th. Its an older building, but very nice, great location, easy to commute too and from. I loved it and dearly miss it.
The one bad part is you only get 2.5/pts per $, and you get 1/3 of the nights.