I love this and this is what we are doing.  I have different approaches and want to run them by you all here.

• We want to have a 30 day free trial
• No Credit Card is required
• The subscription is $X per month afterwards
• During the trial we let the customer know how much time is left and urge them to enter a credit card
• If a card is entered, we will start charging after the trial period
• If the trial is canceled, the trial is canceled :)
• If no credit card is entered, and the trial ends, the subscription is effectively (implicitly) canceled.

One approach I have is to have a "product pair."  One is a trial verison and one is a paid version.

• the trial on the trial version is 30 days and the product expires in 30 days
• the non-trial version has not trial period

If a customer provides a credit card, I move there subscription product to the non-trial product.  The product is just changed. There is no upgrade.  So the trial still remains.

• When the trial ends, the customer is charged with the non-trial product and pricing. There is a credit card on file and we can start collecting or dunning if necessary

If no credit card is ever added, the subscription remains with the trial product.  The trial product 'expires' at the end of trial and so they are never charged (never past due)

My questions are:

1. Is this a good approach that uses Chargify correctly and well?
2. Is there a better or different approach people have used successfully
3. Most importantly for this to work, will the product expire before evern being in a billable state?  I ask because the trial and expiration are at the same "time."  Is there a race condition?

Technically, it appear that the subscription expires shortly after the trial expires (with trial 1 day, expires 1 day the expiration is 8 seconds afterwards in a test)

Unfortunately, it appears that the only way to see when a subscription expires is through the API.   Is this true? There is no way through the Chargify front end?

This approach kind of lost its luster.  With the amount of work required, I'd rather just check in on subscriptions that about to go off trial and cancel them if there is no credit card. With what we have synched in our system it won't be too much overhead as we won't have to poll Chargify for state.