Well, it won't be much of a surprise if I mention Spotify and Netflix for personal purposes. At our company, we also use quite a few subscription-based services like:
as a scheduling tool and content calenar
for keyword analytics
for building landing pages
for external communication
We also use https://brand24.com
, our own subscription-based product that allows as for monitoring our brand mentions as well as industry-related news, or finding potential leads, for instance.