Hey @Valerie Padel 

You can achieve this by using audience rules for your Banner, like the below.

In this case, all the users who signed up 10+ days ago will match the rule (10th day included), and they will see the banner until their signed_up attribute is 13 days ago, which means they’ll see it on 10th, 11th and 12th days.

Once their signed_up attribute is 13+ days ago, they will no longer match the audience rule of your banner, so they will no longer see it.

Hope this helps!