If your subscription isn't showing in your store's Subscriptions section, the usual reason is simple: you're signed into a different account than the one you bought it with.
Check which account you're using
Your subscription lives with the exact Apple or Google account you used to pay. If you're signed into a different one, it won't appear.
On iPhone
In Settings, make sure the App Store is signed into the same Apple ID you used to buy Bend. Then open the App Store, tap your profile picture, tap Subscriptions, then select Bend.
On Android
Make sure the Play Store is signed into the same Google account you used to buy Bend. Then open the Play Store, tap your profile picture, tap Payments & subscriptions, and tap Subscriptions, then select Bend.
Still don't see it?
If you have more than one Apple or Google account, check the others. Your subscription will be under whichever one was signed in when you paid. Once you're signed into your Apple/Google account, you can open the payment screen in Bend and tap Restore Purchases to pull the subscription back in.