How to splitup the value as an array

How to split up the value to an array. I have the whmcs api data it looks like 1,2,3. I need to split up the value to an array value suggest any solution

My api data

Array
(
[result] => success
[totalresults] => 2
[promotions] => Array
    (
        [promotion] => Array
            (
                [0] => Array
                    (
                        [id] => 6
                        [code] => 0UP3NU5J7J
                        [type] => Percentage
                        [recurring] => 0
                        [value] => 15.00
                        [cycles] => One Time,Monthly,Quarterly,Semi-Annually,Annually,Biennially,Triennially,1Years
                        [appliesto] => 1,2,3
                        [requires] => 1,2,3
                        [requiresexisting] => 0
                        [startdate] => 2018-10-22
                        [expirationdate] => 2018-10-25
                        [maxuses] => 0
                        [uses] => 0
                        [lifetimepromo] => 0
                        [applyonce] => 0
                        [newsignups] => 0
                        [existingclient] => 0
                        [onceperclient] => 0
                        [recurfor] => 0
                        [upgrades] => 0
                        [upgradeconfig] => a:4:{s:5:"value";s:4:"0.00";s:4:"type";s:0:"";s:12:"discounttype";s:10:"Percentage";s:13:"configoptions";s:0:"";}
                        [notes] => 
                    )
     )
  )
)

My code is

   @foreach($response['promotions']['promotion'][0] as $key => $value)
     @if($key == 'appliesto')
            
     @endif
  @endforeach

I need to split the following "appliesto","cycles","requires" value as an array.Please suggest any solution

via Chebli Mohamed