You don't get anything for free in life, and that is definitely true for hosting platforms. In exchange for often what is perceived as a great free hosting offer is in fact a very limited service.

Take Heroku's free plan. It can handle a fair amount of traffic but it comes with a very limited database and if your website suddenly attracts a flood of new traffic then you are pretty much screwed. Heroku's free plan is good for early days of development, but it's definitely not a good starting point for your actual product.

A common complaint I hear from those with product ideas is the cost of funding their startup. In particular, web hosting. I've seen too many examples of products trying to run on inadequate hosting plans, often free or very cheap hosting, that fits the budget of the startup in limiting costs, buts increases the risk of the product's site failing to respond should it suddenly find itself on the receiving end of a rush of traffic to the site.

Being a lean startup doesn't mean you should limit your hosting budget so that you only go for free hosting services. You should at least be aiming for a being able to deal with the odd rush of traffic here and there from blog posts and marketing that link to your product. Marketing campaigns through emails and social networks can generate a lot of traffic to your product. With the sudden rush of traffic is your product's hosting platform going to cope? An unresponsive product means lost customers which in turn means potentially lost revenue. Nobody likes to lose money like that.

I'm not saying there isn't a place for free or very cheap hosting. Heroku's free plan is ideal for small static websites and good for test and staging environments for web applications. However for your products, that you want to generate you money, you need to spend a bit of money on a well provisioned hosting platform. This is a professional product you're selling after all, so why not invest some money in ensuring that others see a stable well hosted product rather than a product that times out with even the smallest surge of visitors?

There's plenty of choices out there and they range from bare Linux servers that you require you to set them up to managed hosting like Heroku. The choice is down to the amount of technical know how you have and how far your prepared to roll your sleeves up.

Being lean doesn't mean being cheap, it means providing a stable product that can scale with a growing number of sign ups and customers. That doesn't happen on free or cheap hosting plans, so spend the extra money on your product's hosting to get a stable platform that will be a step to ensuring that you at least get customers signing up.