Nope, it's not allowed legally unless you help to sign in the person then you go elsewhere. The person cannot hold your CC as he/she is not the cardholder.

airports generally are divided into 2 broad areas...land side which means areas open to everybody...check in, arrival wait etc....

airside refers to the secured areas where ONLY travellers can access....so generally means after security/immigrations....if you do NOT have a boarding pass, you cannot enter....and also, all staffs working in the airside needs passes and security checks....

technically, airside in international terminals also means OUTSIDE the country, as you have cleared immigration....

ppl has several lounges in klia2....at the landside, they have ppl gateway, and also manage tgm....and the newly opened aerotel and aerotel ppl....

at the ariside, they have ppl at l gates, wellness spa, and also manage the bar....

obviously for airside lounges, ONLY travellers can use....but the landside facilities, they do NOT insist you must be travelling to use...so many people just go use/eat....

if a card has restrictions, like 5 times annually, then it's ok, people will likely reserve use to when they actually travel....

ambank has no restrictions on how many times you use...

the main problem with both klia and klia2 is that, there is NO lounge available at the domestic airside...no space available...

Good good, another hang out place for me when i go there to pick up people. 
I use to go the PPL at 2M to enjoy their beer there. Now can try here.