I hope there is at least a little pitch to your roof.
Stuff you have is most likely a spray foam insulation covered with silver oxide paint.The same stuff used on metal roofs. I have also seen the silver on asphalt shingles, this stuff lasts a long time.
If you have cracks I would change the roof, water gets into this type and takes forever to get out.Besides that you can never really tell the condition of it with tiny cracks all over.
The new style EPDM rubber roofs last much longer and are easier to repair when you do get a hole. No tar should be used on any of these roofs....eats em up.