You can change your GLIDR tier at any time. Upgrades take effect immediately; downgrades take effect at the end of the current billing cycle.
Where to find tier settings
Go to Settings → Account → Plan. You'll see your current tier and the available upgrade or downgrade paths.
What happens to your data
Your data is never deleted on tier changes. If you downgrade to a tier with fewer projects than you currently have, the extra projects are archived (not deleted) and become available again if you upgrade.