Having done a lot of A/B testing on pricing, don't be worried about playing around with the price via experimentation. As long as you grandfather existing customers.

You should consider doing what newspapers always do, offer an expensive high-end package that you don't expect anyone to buy, then offer a reasonably priced primary version which comes with a big (seeming) yearly discount. Then include a more expensive monthly option.

There's some great books on the subject of pricing. I recommend this one:

https://www.amazon.com/Smart-Pricing-Businesses-Innovation-P...