i have been living and working in bangkok for 5 years and wonder if i can apply for a PR Status under working/business category

Go to the immigration, and ask, I lived in Thailand before for 9 years, always had a one year extension, then the immigration asked me, why do you not apply for a permanent residence permit , so I did, it was a lot of trouble, but one and half year later I got it, then I left Thailand for more then one year and I lost my residence permit again, and live know on a year extension again

The first criteria for application is three years on one year extension of stay from Immigration. If that is how you stay read the pinned item for details of what may be required to pass review panel as there are other things that you must have to stand much of a chance for approval. But if you can meet the requirements it is likely a good idea to obtain if planning on staying here.

Also worth mentioning that there has been no PR issued since 2006? Or some year like that? (I think)