Credits are spent for getting valuable information. If you want to contact anyone, send him/her a message, it will cost you a small amount of credits. Credits are used to upgrade membership levels and gaining the access to the areas of your interest as well.

Membership upgrade:

You can spend your credits by upgrading your account to silver, gold, or vip status. Know more about account upgrading benefits and costs by pressing Upgrade buton in the control panel.

UpgradesMembership levelMontly subscription Yearly subscription
Bronze level Free Free
Silver level 7 40 - you save 44 credits
Gold level 15 100 - you save 80 credits
VIP level 25 200 - you save 100 credits

General costs:

If your are Bronze member sending email to any other user - 0.3 credits
If your are Silver member sending email to any other user - 0.2 credits
If your are Gold member sending email to any other user - 0.1 credits
If your are VIP member sending email to any other user - free

Opening messages and replying doesn't cost anything

Flirt zone:

Sending flowers costs 0.1 and it is valid for 1 week
Sending kiss costs 0.1 credits and is valid for 1 week
Throwing an egg costs 0.2 credits and is valid for 1 day
Throwing a tomato cost 0.2 and is valid for 1 day

Note: all VIP members are "bulletproof" for eggs and tomatoes.