Niek,
You can reset your AVG My Account password to resolve it. We have sent you the password reset email to proceed further.
Refer this article: http://support.avg.com/SupportArticleView?urlname=Activate-AVG-Zen-Protection-Performance-or-Ultimate to activate your AVG TuneUp - Unlimited (1 year subscription), AVG Internet Security - Unlimited (1 year subscription) and AVG Secure VPN (2 years subscription) using your email address and password.
Let us know if you face any difficulties.