SHIRISHPAREKH I understand, but the problem is that I don't see your donation in the Google donation list on my account.
So I need the confirmation mail you have got from Google.
In this mail there is an order number and with this number I can check the status of your order with Google.
Anyway in the meantime you can use this code to get all features:
Open COL Reminder and tap on the 3 dots, now About and on "Donate".
In the "Donate" screen tap again on the 3 dots and select "Code".
Enter the code above and it should work afterwards.