Do you offer a subscription model to your clients for your services?

Question

I am considering completely changing my pricing model to instead of charging per project (I do whiteboard animations in the main), charging a monthly fee, which will include a number of projects throughout the year.

I interviewed an accountant the other day on my podcast and he's disrupting the accountancy industry by charging just £99 per month, including all work, with a few add-ons.

I'm interested to know if you are already offering a subscription model for your services and what are you charging per month and how long do they need to stay paying to recover your costs and make a profit? I've calculated that they would need to pay for at least 18 months @£99 to make it pay for the smallest animation project.

'Customers' are a one-off, you're not necessarily going to see them again, 'Clients' are an ongoing relationship with your business."