I have mixed feelings about subscriptions depending on the case:

a) the subscription is a red flag stopping me from using the service (Notability, Ulysses)

b) righteous anger for subscription based apps which were already making tons of money without subscription but switched to it anyway (looking at you, Adobe)

c) the subscription model is somewhat justifiable given the complexity of the end product (Altium, Autodesk)

d) I am willing to pay monthly fee because the app or service is actually way better at some things compared to non-subscription analogs (Spotify)

e) this is not a monthly fee but a monthly donation you can stop paying at any time (Wikipedia)

So, when exactly is the subscription fee appropriate for you?