The 23-year-old midfielder spent time with Liverpool and Leicester City earlier in his career, but struggled to make an impact at either club.
Since then he has taken in spells in Sweden and Belgium, with Standard Liege prepared to sanction a move during the winter transfer window.
Ajdarevic claims to have settled quickly at The Valley and is ruling nothing out as he tries to convince Addicks boss Chris Powell that he is deserving of a permanent deal.
The former Sweden U21 international told Expressen: "The pace is tremendously high. I feel better and stronger than I have ever been.
"I already feel that I have made progress and it is a different type of game to what I am used to.
"Some matches are just about running, but other times we try and play along the ground as we should.
"It has gone well. The most important thing is that I get to play.
"Everyone knows what I have gone through at Standard, but that is the past. I am happy it is going well for both the club and for me personally."