Short answer
A one-time credit purchase adds credits to your balance once and does not renew. A subscription adds credits automatically each billing period and renews until you cancel it. Credits from either source are spent the same way.
One-time credit purchase
Charged once — there is no recurring payment.
Credits are added to your balance a single time.
Typically costs a bit more per credit than a subscription.
Buying a credit pack is not the same as subscribing — it does not renew.
Subscription
Credits are added automatically each billing period.
Renews automatically until you cancel it.
Costs less per credit and may include order priority, depending on the plan.
For details, see What is included in a subscription.
Which one did I buy?
If the purchase renews on a schedule and appears as a subscription in your App Store or Google Play account, it is a subscription. If it was a single purchase of a credit amount that does not renew, it is a one-time credit pack. You can check and manage subscriptions in your App Store (Apple) or Google Play account.
Frequently Asked Questions
I bought a one-time credit pack — will I be charged again?
No. One-time purchases do not renew. Only subscriptions renew automatically.
Are one-time and subscription credits used differently?
No. Both are spent the same way on any service.
How do I cancel a subscription?
Subscriptions are managed and cancelled through your App Store (Apple) or Google Play account.