You can absolutely store IP addresses (and other personal information) without consent and be GDPR compliant. You just need to explain what you are storing, for

You can absolutely store IP addresses (and other personal information) without consent and be GDPR compliant. You just need to explain what you are storing, for what purpose, who you share it with, how long it's stored, and comply with the "rights" put forth in the legislation. GDPR merely constrains what information Google can share without your consent and requires them to be more explicit in stating what information they gather about you.