I have made a desktop application in kivy and able to make single executable(.app) with pyinstaller. Now I wanted to give it to customers with the trial period of 10 days or so. 
The problem is how to make a trial version which stop working after 10 days of installation and even if the user un-install and install it again after trial period get over it should not work.
Giving partial feature in trial version is not an option.
Evnironment
Mac OS and Python 2.7 with Kivy
My idea is

Make a table in database
Use datetime module and put system date in that table  as begining date
Use timedelta module timedelta(15)( for calculating the date that program needs to be expired here i used 15 day trial in code) and store it  in  table of database as expiry date
Now each time your app start put this logic that it checks on if current date is matches with expiry if it does show error it is expired of your explicit logic

Note:- make sure begining and expiry runs only once instead date will be changed again and again.
How to make trial period for my python application?