To upgrade the subscription:

•  go in the app 

•  go to Profile

•  click on 'My subscription'

•  click on 'New subscription'

The app will display the full price, but you will of course only be paid the difference between the new subscription and what you did not use during the previous subscription.

Send us an email to info@bsit.com when you have made the change and we will send you the proof of payment issued by the company that does the payments. (Paying agency: Stripe)