If can be useful for historical newspaper data, but that depends on where you're researching.
Can you view the list of newspapers and dates it covers before committing?
Assess that and then make your decision. I wouldn't commit for more than a year, that's for sure.
I've found some useful data using this site, however I shutter to recommend it, because of one MAJOR issue. You can't cancel your subscription on-line, you must call to cancel. They don't inform you by email when your subscription is rolling over and you will be charged at a much higher rate.
If you do subscribe, make a note to call and cancel your subscription before it rolls over. I always request a confirmation email that I've cancelled the subscription.