GDPR and clients photos on social media? Hi there,

I don't really know can I use my clients photos from beauty salon (hand nails, eye lashes etc..) to publish to FB/Instagram or do I need written consent in order to do so?  
I have a beauty salon with regular clients that are aware of this, approve it and are also my followers, so far I had no problems with doing so, but I ask just to be sure.

Thanks