Why did an advertiser's campaign pause by itself?

Wcart pauses a sponsored campaign automatically in these cases:

• Wallet empty: the advertiser's ad wallet couldn't pay for a click. Add funds from Plugins → Advertising → Advertisers → Wallet.
• Daily budget reached: the campaign spent its daily budget for the day.
• Total budget reached: the campaign hit its lifetime budget.

You can see a campaign's total Spend on the Campaigns tab.

If you Suspend an advertiser yourself, all of their campaigns stop showing on your store until you Approve them again.