We use Smart Offers on our online learning platform. Its the only plugin with all the functionality needed to upsell your customers effectively. For example, the offer presentation is fully customizable, you can create if/then funnels and prices can be set independent of the original price. – The support is great and highly individual. We had an issue with our server integration, and got great support from the team, resolving the issue quickly and professionally. Highly recommend if you are looking for a top notch upsell plugin!