To assign a package to a client, go to the Clients tab then select your client to pull up the profile:

Open the 'Services' tab, click on the '+ Assign Package', button to select the appropriate package.

Choose any options you'd like to set...

As a trainer you can assign packages to clients and setup the payment for the package to be paid in split payments over time. 

For example, a client may want to purchase a $100 package but pay it off over 4 weeks at $25/week. As long as you have a payment integration added, and the client has stored payment details, you can enable the option 'Create split recurring payments to pay for the package' while assigning a package, followed by choosing the split payment period arrangement.

Make-Up Package
If the client's package hasn't run out yet, you can manually adjust the total number of credits available in their 'Packages' list:
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For those without an assigned package, you can create a Make-Up Package that would compensate for the cancelled/missed booking.
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To do so, follow the steps to create a regular package, and set the number of sessions or classes to the number that the client has missed. You can set the price to $0, or a different amount if you want to charge them. Once created, you can then go ahead and apply the package to their account.
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​Related articles:
​Assigning a Membership to a client
​How to modify the number of credits for assigned Packages/Memberships