Often times when people ask why they haven't been upgraded, the issue is as a result of making multiple accounts, then upgrading 1 of them, and then using a different one, which is still free. If you have done this, log out in the app, and login into your upgraded account.
If you paid via Paypal and were not upgraded and you're sure you only made a single account, this usually means you used your bank account as a source of funds. These payments are not instant and take 3-5 business days to clear. If you look at the transaction details in your Paypal account you will see the date when the payment will be cleared. As soon as that happens, your Windscribe account will be upgraded.
If you got a voucher, make sure you haven't already claimed the voucher on your account during the signup process. To verify, login on Windscribe.com, go to your My Account section, and scroll down to Payment History. The voucher should appear in the list. If it doesn't, then you probably made a 2nd account. Contact support if you don't remember what the account is, and be sure to provide the voucher code.