Subcriptions are great! The premise that you are paying monthly for a number of meetings is very good.
However, if you want to have them as a reliable source of income it would be great if you could set up a minimum/maximum duration to them in weeks/months. Right now, everyone can just cancel at any time...not very good for a business.
Pros:
for you - you have a reliable source of income you can depend on in advance (say: 100$ a month for 3 months)
for your clients - define a contract length, so they wont get charged longer than the subsription allows (you can also disable it) - say after 12 months the subscription end by itself.
Cons:
the only one is that your clients cannot quit the subscription in less time than the minimum you set (not really a big con...because they can see the subscription details before paying)
Mitigation for the con:
implement a trial period, when they can quit the subscription within the first x days/weeks