HTR is a utility token and the native currency of Hathor Network. It will always be the gateway to the current and future services possible on the platform. Right now, the most notable use case is minting your own token, something anyone can easily do with the Hathor wallet and without a single line of code. Future services they have planned on the network, like Nano Contracts, side-DAGs and so on will also use HTR in a similar way. Hathor is still studying the best model to do it.