Every Pay-as-you-go purchase includes both Residential and Mobile. One balance, spendable on either.
Buying traffic
1
Open Pricing
Click Pricing in the left navigation.
2
Choose an amount
Choose the amount of traffic you want.
3
Buy traffic
Click Buy traffic.
4
Pay
Complete the payment.

Your traffic does not expire
Pay-as-you-go traffic does not expire. There is no monthly cycle to run out of, so nothing freezes and nothing lapses. Traffic left over from one purchase is still there when you buy again, and the balances simply add up.Pay-as-you-go or a subscription?
Pay-as-you-go costs more per GB. You are paying for flexibility. If your usage is steady month to month, a subscription is cheaper. The Pricing page has the current rates on both, and how monthly subscriptions work covers the other side.