On or about the date of conclusion of the trial, send a notice:

   Your trial is about to end. To continue receiving services, 
   please make payment of {PAYMENT_AMOUNT} by {DATE}. You will
   need to authorize recurring payments in the amount of
   {PAYMENT_AMOUNT}. You can do that by clicking {PAYMENT_LINK}.
   If you would like to cancel the trial click {CANCEL_LINK}.

   Please note that if we do not hear back from you by {DATE},
   we will have to temporarily discontinue the service/product
   until you authorize recurring payments.