Most scoring models ignore rental payments. However, if you have no credit history at all, banks will see your payments as a positive. That could mean approval for an installment loan or an unsecured card rather than secured. In other words, your profile is helped even if your scores don't reflect it.
Including rental payments might also be helpful if your file is both very young and very thin. If your profile has more than a couple of accounts and they've aged a bit, reporting rent may do more harm than good.
Some lenders are using alternative scoring when option A for them fails, and there's a big push in the financial markets to be able to lend to people who don't have a traditional credit report, so it might help.
Also since you have to declare on many / most applications in my experience what your housing payment is and if you rent or own, having the rental history there can't hurt is my thinking.
I wouldn't pay a fee to do it nor would I really worry much about it if I had a thick file already, but if I were a thin/new file and I could tack it on for free, I probably would.
Our OP has multiple credit cards and multiple loans... see post #1 in this thread:
So he wouldn't fall in the unscorable group Heaven and R are thinking of.
I think you should hold off on paying money to add rental history. Take another week to talk to us about it. Adding rental history will not alter your FICO mortgage scores.
Given the fact that you have multiple cards and loans, you are not an unscorable consumer. Furthermore, if you simply do as you plan (in the other thread on which you are getting advice) -- which is to pay all cards to zero except one with a small balance -- you should have a decent mortage score. If a lender really wants to consider your rental history (improbable given that you will already have decent mortgage scores) you can supply that lender with the rental documentation at that time.