There's a good chance that this actually isn't an app. In fact, you could replicate this by utilizing your product vendor field as a way to disclose the limited time offer. Here is how it can be done:
The code used in the vendor field:
<p style="color:red"> <b> Shipping: 5-10 Business Days </b></p>
If you don't want any color or bold text styling, you can simply enter in the text. Then, once you are done running the offer, you can remove the text from the vendor field. Also, you can replace where it says "Shipping: 5-10 business days" to "offer ends Saturday the 5th of December"
I hope this helps! If there is anything else I can help you with, please let me know.
thank you for your answer, this actually is a good alternative. I´ve seen this app in several shops, i am actually pretty sure its an app. The thing is i want it to update it self everyday, this means everyday it should say "Offer ends on "today the....". Otherwise i would have to update it every day at 0:00 am.
This would vary depending on how your theme has hardcoded the styling for the vendor field. In your case, it would be set to all capitalization. You would need to go into your theme files and edit the code to change its font styling.
If there is anything else I can help you with, please let me know.