How do sales commission for selling services work?

[sales]

Hi,
M friend's husband wants me to help him sell a service he's developed for companies. It's basically signing up to some software he's developed that would be very useful for certain types of companies. I won't give too many details so it can't be identified. But first of all he wanted me to do the sales and marketing. Basically visiting companies demonstrating what the software can do for them then getting them to sign up for the service. Once they sign up they will pay him a monthly fee. I am happy to do this as I think the service is a great idea and companies will go for it, so I won't feel like I'm trying to sell a complete lemon. In fact we've tentatively approached a few companies and had very good response and two are already signing up out of four approached.
They would pay about a monthly fee of £50, but I think we may adjust that fee depending on how big the company is. The fee is also per branch, so I may approach one office and get 50 branches signed up from just one meeting.
I firstly thought I'd like shares on the company to do this work as I'd love to get in on it as I think it'll be big, but he's not keen on doing that and wants to offer me commission on sales.
My question is: what should I ask for, for example if I have a meeting with a company manager and from that I get that company (with 60 branches signed up all for £50 per month per branch) I guess I get 10 or 20 % of that figure, but for how long? Do I get 10 or 20 % of the monthly fee for as long as that company stays signed on with him? What if I just get 6 companies onboard then feel I can't work with the guy and don't carry on or he dumps me. Do I them carry on getting that 10 or 20 % because of course without me making that initial sale he wouldn't then be getting that money in each month.
I mean for selling a product it's straightforward you sell 10 vacuums then leave the company, you walk away with your 10 % of the vacuums sale price or whatever. But in a business where the money will keep coming in, in the way of a monthly fee, how does it work.
I can lead him as to how it is to be structured as he hasn't a clue either how it works.
Advice please!

I'm paid commission on services, interestingly the above sounds like a bizarre way to sell software if thats what it is (I would have expected an upfront purchase price and then support costs annually...) anyway, for services sales I am paid a % 'win bonus' based on the total contract value eg using above 60 branches, £50pm= £3k pm, 12 month contract= £36k tcv, cost of product =£25k, 5% upfront win bonus= £550. I would then be paid a monthly further 5% on the actual margin generated. I would assume most companies would pay commission as a % of margin if you will have any control over the sell price. Does that make sense?

Ignore what i said about it being a bizarre way to sell software, I've not long woken up and still have a fuzzy head... I'm sure you mean a 'software as a service' type set up...

Hi there,
Yes it's a software as a service type of setup.
Excuse my ignorance I haven't worked in this way before. what's tcv?

Oh doh! Does it mean total contract value? And I've been awake for hours......

Cost of product?? Do you mean the service you sell they pay £25K to buy it then a monthly fee on top of that?

To attract people to buy into it I think he wants to ask them to pay the whole 12 months fee upfront then they can withdraw at any time and will be paid back whatever remains of the 12 month fee. Not sure how that would work in temrs of my fee, and is that a crazy way of doing it anyway?

Embarrassing I don't know what margin means.....

so... margin is basically top line profit, selling price less cost of goods/services. the ability to withdraw then refund is a strange one, unless its something which would be difficult to transition off of and they are trying to seed it into an organisation. I'd always expect a defined contract term, with termination only for a serious service level breach. Yup TCV is total contract value. I guess commission is only part of your total package so you need to work out what is achievable and acceptable to both parties. If his drivers are purely new business wins then you could be targeted and bonussed against this rather than revenue/margin and review this once the company is more established...

I don't know what "transition off" and "seed it" means! Or "drivers" and "targeted". I have stepped into a strange new world...
Would it be totally unusual to just have the commission as your pay, no actual salary?