About your AdMob account limits
Your AdMob account has maximum limits on areas like the maximum number of active ad units you can have. While you'll likely never notice them, keep these limits in mind when planning monetization, campaigns, and mediation in AdMob.
The following table shows the limits for different areas of your account.
|Ad units||20K active|
|3rd-party mediation line items||50 per ad unit|
|Campaigns||10K active or paused|
|Campaign ad creatives||4M active or paused|