Almost every switch under Settings → Customer portal reads "let customers do X". A few read the opposite, and they live in their own section, below everything they hold back, so that switching the page on from top to bottom does not quietly restrict your subscribers.
Two switches, both about the first renewal:
Customers cannot change their subscription product until a renewal has been paid. It hides swap, add and remove.
Customers cannot skip an order until a renewal has been paid.
In both, what the customer paid at checkout does not count: the lock lifts once a renewal has actually gone through. That is the setting to use when you sell a starter box and want the first delivery to arrive as sold.
It is also the setting most likely to confuse you later. Turn it on, build a swap rule, open your own customer account on a subscription that has only ever been charged once, and there will be no swap button. The rule is correct and live; the limit is hiding it.
Separate from those, and only about cancelling: Payments required before a customer can cancel. 0 means no minimum. Set 12 and a monthly subscription can only be cancelled from the customer portal once twelve payments have gone through, the one at checkout included.
A customer who has not reached it sees how many payments are left instead of a cancel button, so make sure they have an easy way to reach you. It never binds your hands: you can always cancel a subscription yourself from Subscriptions.
All three apply on both billing engines, so a Mollie-billed subscriber is held to the same terms.
A commitment your customer did not agree to at checkout reads as a trap. Say it on the product page, in the plan name or in the widget text, before they subscribe.
Some markets regulate this. UK stores in particular should read "Cooling-off cancellations and refunds (UK stores)" before setting a minimum.
Stuck on any of this? Open the chat in the bottom right corner of the app and we will help you set it up.