[Grammar] have been and am working

[Snappy]

According to Longman English Grammar (L. G. Alexander),
I've been working for Exxon for 15 years (Depending on context, I am still now, or I may have recently changed jobs or retired.)

Then, do I have to say, "I've been working for Exxon for 15 years and I am still working for Exxon," if I want to say that I am still an Exxon worker?

 

[5jj]

The normal assumption will be that you are still working for Exxon, so there is no need to add that.