With Clientrol, you can offer your services to your clients
1) Hour Plans (i.e 1 Hour, 5 Hours) or any nunber of hours.
Your Client can purchase these Hour Plans by Stripe or PayPal.
2) Bundle Plans (i.e Social Media, Tech Support, Marketing etc)
You can offer Bundles to your clients who can purchase them as a once off, Monthly or Annual.
I use Clientrol now for al my clients, very happy with it so far and great support. Happily recommend.