Il you are a website developer, you are not "allowed" to create membership accounts for your clients. As a member you may create many accounts, one for each client, but you can't create a full membership account and share it with your client.
They don't offer a pure pay-as-you-go plan based on resources (CPU, disk space, bandwidth). Starting at $1.99 /mo or 0.003 /hour, as any other mainstream providers, you have to pay a fixed periodic amount. They should be disqualified as a recommendation for this list.