If you have a page online for your business, especially a social media page, you have a virtual store of sorts. No, you do not have to have an ecommerce site to drive sales. Instead, every page that you have and every interaction that you put out there is the potential for profit. Even free likes and free followers can be converted into money for your business. As such, you need to consider them as moneymaking entities.
The reason that free followers can be seen as money is because they ultimately are connecting with your business. Even if it is in the smallest of ways that they interact, they are trying to connect with your business. As such, you should look at this as a potential customer that can come to your business and will likely stay with it as well. For that reason, make sure that you are building your business around engaging and encouraging this engagement from others. It is a sale waiting to happen.