Yes! You can extend a subscription using Paypal payment method on the Account Control Panel.
Ho to do this:
1/ Open Account Control Panel
2/ Sign In with registered VPN Shield app login, or register the new one if you don't have it
3/ Select one of subscription plan and click on "Purchase" button.
4/ Follow the Paypal payment
When purchase completed on website, login to your VPN Shield application and start use VPN.