For every HubSpot product: Marketing Hub, Sales Hub, Service Hub, CMS Hub, Operations Hub, HubSpot offers four tiers of subscription:
Of course it all starts with the functions you need and requirements you have for the system.
It is totally legit to start with free subscription and use it for some time.
But when you think about full featured product - it is Professional and Enterprise tiers.
There are four types of discounts that you can expect to get when buying a new subscription from HubSpot: