Question about Retainer Service ?

[Umo]

Additional retainers can be used until the end of a billing period even if you reduce the number of additional retainers during your subscription period. Also, even if a subscription is cancelled, additional retainers can be used again once you reactivate a subscription.

*Any items stored on additional retainers will be maintained as long as the retainer is not released from service while in-game. It will be possible to retrieve the stored items, as well as receive rewards for ventures, when you are once again able to utilize the additional retainer.
* Please note that any additional retainer subscription cancellations will take place at the end of the current billing cycle for credit card and Crysta users.

Source: Introducing New Optional Services (03/27/2014)