will my client’s website work in that particular domain? And next month if I want to change something on that website then will I able to do this?
Hey there. 
Site hosting plans automatically renew every month.
If your hosting plan is cancelled or payment fails your website it will automatically unpublished and the custom domains removed.
You will still have access to the project in your Webflow Dashboard, however you may be limited in editing if you do not also have an Account Plan.