Lifetime deals have several key points to consider.
1. Look at the pricing for the Scalenut lifetime deal. The benefits of the deal could be limited compared to retail pricing especially if they offer a free plan.
2. Look at reviews from current clients and people who just bought the lifetime deal as this will give you a good idea of whether Scalenut is here for the long term.
3. Look at their product road map to see if their vision matches your requirements for the future.