Cloud providers see Pay-As-You-Go subscriptions most popular 

Cloud Services
There are many cloud computing service providers which are offering different types of cloud computing services, such as PaaS, IaaS and SaaS, for reasonable and low prices. 
A peep through some of the leaders’ offerings shows all of them have adopted pay-per-use strategy for the basic usage. However, prices vary depending on the type of cloud service a customer is adopting, making a comparison less accurate.
Amazon Elastic Compute Cloud (Amazon EC2) is a web service that provides resizable compute capacity in the cloud. It is designed to make web-scale cloud computing easier for developers.
The pricing of the product is based on the usage and there is no minimum fee. New AWS customers can get started with Amazon EC2 for free. Upon sign-up, new AWS customers receive EC2 services each month for one year. 
On-Demand Instances let to pay for compute capacity by the hour with no long-term commitments. This frees users from the costs and complexities of planning, purchasing, and maintaining hardware and transforms what are commonly large fixed costs into much smaller variable costs.
Microsoft’s cloud, the Azure, also has a flexible pricing list, with the company offering pay for only what you use, the same as AWS. Azure is available for purchase in 140 countries around the world and support billing in 24 currencies.
The company says its Pay-As-You-Go subscriptions are most popular and flexible payment plan. There are no minimum purchases or commitments and one can cancel anytime.  A buyer can pay for them by credit-card as well as by invoice.
Microsoft’s 12-month prepaid subscription for Azure services let you to earn discounts on the amount a buyer prepays. If your service consumption exceeds the prepaid amount, you can make an additional prepayment to continue getting the discount or simply pay as you go for future usage. 
The company also says one can work with the same resellers that you already purchase Microsoft software from using the Open Volume License Program. If you have already purchased Azure from a reseller and have an Open license key, you can activate your Azure subscription or add more credits to it.
Meanwhile, large organisations often sign up for a Microsoft Enterprise Agreement. By making an upfront usage commitment to Azure they earn several additional benefits—including flexible billing options and our very best prices.
Rackspace also offers pay-as-you-go pricing model. For the Managed Infrastructure category, the company charges $50 per month after the first 30 days across all Cloud Servers. For managing entire cloud operations in an enterprise, Rackspace asks a minimum service charge of $500/month across all Cloud Servers. The rate for both managed infrastructure and managed operations is $2,500 per month.
Google claims that its Cloud Platform is up to 40 percent less expensive than other public cloud providers. It has given a long list of pricing on its website based on different cloud service it offers. Among the list, Cloud Dataflow batch mode is priced at $0.01 per Google Compute Engine Unit per hour. Meanwhile the streaming mode is charged $0.015.
Google Cloud Storage pricing for standard storage is $0.026 per month, durable reduced availability storage is charged $0.02 and nearline storage is $0.01 per month.
Though pay-per-usage is the most popular payment system for cloud services, charges vary in line with the type of services one is embracing. The popularity of cloud adoption is likely to increase in a world increasingly dominated by connected devices and mobile users and where corporate data is moving to the cloud. 
Arya MM