What would be a good CRM recommendation for me?

I’m looking to create a subscription based company that provides services monthly on certain days.

I want clients to be able to use a website to pick out one (or more based on tier of package) day of the month to receive my services. They would do this for every month they’ve subscribed for and can be changed in the future.

I’m not sure which crm would be able to do what I want.