Node providers are essentially teams that offer access to Nodes without having to run your own node. So instead of sending your requests to a local node, you can send them over the internet to a provider offering an identical API that is running fully-synced, up-to-date nodes available 24/7.
Which is essentially the problem you're having in the first place. There's no reason to pay for a service that offers access to the blockchain, because firstly, that's available for free, already, and second, you don't get the benefits of running one yourself. Benefit such as privacy, verifiability and ultimately, self-sovereignty.
developing on your own node connected to the network can be particularly annoying.
1) because it can take a lot of time to set up a node - up to weeks! The bane of any developer is spending a lot of time setting up for a tool that doesn't directly contribute to what they're trying to build, and nodes are among the worst offenders.
2) because nodes have to be managed: Nodes regularly need to be upgraded every few weeks, and occasionally re-built from scratch. Individual nodes can fall behind the network for various reasons.
3) if we’re speaking about a single node, it’s fine and dandy especially when you're building a personal project. But what happens when you can't make your node server large enough to keep up with the requests you're sending it?
We give a free period for using our service and letting you choose whether you like it or would you like to it yourself.