Can I change employers while on a D1 residence permit in Portugal?

The D1 is tied to subordinate employment, so your status depends on remaining employed. You are not necessarily locked to a single employer for life, but the permit exists because of your work in Portugal.

When you renew your residence permit, AIMA wants evidence that you are still working in a qualifying role — either with the employer named in your original application or in a new comparable job. If you change employers, keep proper documentation of the new contract so you can demonstrate continued eligibility at renewal time.