Total expected to pay on monthly: $15 x 12 = $180
Represented by:
Amount paid: $15 x 5 = $75
Total no longer payable $15 * 7 = $105
Total due for perpetuity: $199
Equals total for this year of $180 - 105 + 199 = 75 + 199 = $274.
Total expected to pay on annual (full price) $199 x 1
Represented by:
Months consumed: $199/12 x 5 = $82.92
Months remaining: $199/12/ x 7 = $116.08
Total due for perpetuity: $99
Equals total for this year of $199 + $99 = $298
So the real difference here is not between the models, but the fact that there was an incentive earlier in the year to get on the annual program. Dreamstation has a point if the retrospective special price is taken into account, but that is not the actual price for the product - the actual price is $199, and the intrinsic value remaining in the subscription, regardless of what was paid for it, is $199/7 assuming 7 months remain.