I am an app developer, thinking of releasing an app development service, where I can charge my customers monthly or annually and release their apps from my account on app store. Will this violate the terms of app store?
I can ask my customers to accept the apps store terms and conditions. :)
An "easy" way to get by this technicality would be to publish the app as your own (IE, from your account) and have it written in to your site's TOS that the app would be published by happyhardik (or whatever your account's name would be) on their behalf, with all credit regarding the app going to them. It basically makes you a mediator between the iTunes Store and publishers.
Be aware, however, that doing this might cost you more time and effort that it may be worth. You'll have to be the contact person for each of your users if/when the app is rejected by the store and will have to forward that message on to each affected user. Too many failed attempts at publishing may result in a temporary upload or submit ban on your account, so keep that in mind as well. Perhaps you could allow users to input their store data (IE, username and password) securely and use that to upload their items on their behalf?
If feasible, you could allow your users to download their raw, compiled data and let them upload it from their own account. It would take you out of the uploading hassle altogether and would keep your own app maintenance to a minimum.