Please, go to your User Office at https://my.keepsolid.com/. Log in with Google/Facebook account (this option is below 'Forgot password?'). Click on your KeepSolid ID at the top right and select Set Password (Create a new password for your account).
This way you will be able to login without using Google/Facebook account. You will need to enter your email and the password you've created.
In this case you’ll need to contact Apple support directly: https://support.apple.com/, or make a purchase directly on our website instead:
https://www.vpnunlimitedapp.com/en/pricing.
In case if you cannot make the in-app purchase on any Apple device, you’ll receive the alert Your Purchase Could Not Be Completed.
This is the common issue of iTunes Store faced by 20% of our users. The reason is that the iTunes Store is unable to process your purchase due to the reasons beyond our control. To complete the purchase, please go to the User Office or check out Pricing on KeepSolid VPN Unlimited website, choose the needed offer, and follow the instructions. If you still can’t complete the needed purchase, please contact our technical support at support@keepsolid.com
In case if you want to complete the in-app purchase and you don’t want to buy it on our website, please contact iTunes Support at www.apple.com/support/itunes/ww/