We reward customers with double the days left on their trial if they purchase before their 14 days are up.
For example, if you sign up for a trial and purchase 4 days into it, you will get 20 free days at the end of your first paid month.
Note that this will also move your billing anniversary date by the number of free days for your second and subsequent months.

E.g. If you started a free trial on the 1st of March and then purchased on the 4th of March you would be billed for the first month at the time of purchase (March 4th). At the end of the first paid month (April 4th) you would start the 20 free days bringing you to April 24th. On April 24th, you would be billed again for the next month which runs until the 24th of May.